Magnitude and direction Definition and 202 Threads

Absolute magnitude (M) is a measure of the luminosity of a celestial object, on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it were viewed from a distance of exactly 10 parsecs (32.6 light-years), without extinction (or dimming) of its light due to absorption by interstellar matter and cosmic dust. By hypothetically placing all objects at a standard reference distance from the observer, their luminosities can be directly compared among each other on a magnitude scale.
As with all astronomical magnitudes, the absolute magnitude can be specified for different wavelength ranges corresponding to specified filter bands or passbands; for stars a commonly quoted absolute magnitude is the absolute visual magnitude, which uses the visual (V) band of the spectrum (in the UBV photometric system). Absolute magnitudes are denoted by a capital M, with a subscript representing the filter band used for measurement, such as MV for absolute magnitude in the V band.
The more luminous an object, the smaller the numerical value of its absolute magnitude. A difference of 5 magnitudes between the absolute magnitudes of two objects corresponds to a ratio of 100 in their luminosities, and a difference of n magnitudes in absolute magnitude corresponds to a luminosity ratio of 100n/5. For example, a star of absolute magnitude MV=3.0 would be 100 times as luminous as a star of absolute magnitude MV=8.0 as measured in the V filter band. The Sun has absolute magnitude MV=+4.83. Highly luminous objects can have negative absolute magnitudes: for example, the Milky Way galaxy has an absolute B magnitude of about −20.8.An object's absolute bolometric magnitude (Mbol) represents its total luminosity over all wavelengths, rather than in a single filter band, as expressed on a logarithmic magnitude scale. To convert from an absolute magnitude in a specific filter band to absolute bolometric magnitude, a bolometric correction (BC) is applied.For Solar System bodies that shine in reflected light, a different definition of absolute magnitude (H) is used, based on a standard reference distance of one astronomical unit.

View More On Wikipedia.org
Recent contents Top users
  1. inigooo

    Find the magnitude and direction of the velocity

    V^2= u^2 +2gh
  2. F

    Intuition on the direction of friction in a rotational dynamics problem

    The figure illustrates the situation. The radii of the larger and smaller discs are 2R and R, respectively. Their masses are M and 2M, respectively (the largst disc has the smallest mass). Also, m=5/4 M, where m is the mass of the suspended object. The pulley is "massless" (negligible moment...
  3. J

    Magnitude and direction of k vector

    I didnt understand the question. The magnitude is 2(pie)/wavelength. I get 78500 rad/cm which is pretty wrong as guess. Where would angle come into picture? Ref: https://www.millersville.edu/physics/experiments/062/index.php Shouldn't direction be like i + j + k ? So will it be like: |k|cos30...
  4. P

    Magnitude and direction of current

    I am struggling with the angles. Since the conducting wire is moving down for it to be stand still, the force should be opposing it, hence the current should be from Right to Left. I am confident of the Force direction and its value is if ## I ## is the current ##F = ILB (N)## since L and B...
  5. P

    Find the magnitude and direction of the Magnetic field required

    i tried to draw the directions of the parameters The direction of B is clear since then the Force will be in the positive X direction. I am bit confused with the direction of Force, how would i draw it and the components. Is the gravitational force i have drawn is correct? Do we have better...
  6. Abdullah Younas

    Finding the magnitude and direction of a boat's motion

    Homework Statement: A boat is traveling upstream in the positive direction of an x axis at 14 km/h with respect to the water of a river. The water is flowing at 9.0 km/h with respect to the ground.What are the (a) magnitude and (b) direction of the boat’s velocity with respect to the ground...
  7. themountain

    The magnitude and direction of the minimum magnetic field

    F=ILB F=(48)(.76)B F/36.48=B I am stuck at how to find F, is there a different formula I am missing?
  8. P

    Calculate the magnitude and direction of the torque

    Homework Statement [/B] a) (a) Assuming the HCl molecule consists of point-like ions (H+ and Cl) separated by 1.0 * 10^-10m, find the dipole moment of the molecule. b) Calculate the magnitude and direction of the torque exerted on this dipole if the molecule is subjected to an external electric...
  9. isukatphysics69

    What is the magnitude and direction of the electric field

    Homework Statement What is the magnitude and direction of the electric field at the position indicated by the dot in the figure below? Give your answer in component form in the blanks below. What is the x-component of the electric field at the indicated point? Homework Equations kq/r^2 The...
  10. karush

    MHB Eb 4.d determine the magnitude and direction of V

    $\tiny{\\ eb 4.d}$ $\textsf{If $v_x=-9.80$ units and $v_y=-6.40$ units,}\\$ $\textit{determine the magnitude and direction of $V$.}$ \begin{align*}\displaystyle magnitude&=\sqrt{(-9.8)^2+(-6.4)^2} =\color{red}{11.7047}\\ direction&=\arctan{\left[\frac{6.4}{-9.8}\right]}...
  11. S

    Electrostatics? Magnitude and direction of a magnetic field

    Homework Statement A force of 2.4N is exerted on a -1.8µC charge in a downward direction. What is the magnitude and direction of the magnetic field at this point? (The assignment sheet is called "Electrostatics Questions", hence the "Electrostatics?" in the title) Homework Equations Electric...
  12. P

    Magnitude and Direction of the Force on a Charge

    Homework Statement What is the force F (a vector) on the -10 nC charge in the figure? Give your answer as a magnitude and an angle measured cw or ccw (specify which) from the +x-axis. The figure shown is in the shape of a rectangle. On the top left is a +15 nC charge; on the top right is a...
  13. S

    Finding magnitude and direction of reaction force

    Homework Statement A uniform horizontal rod of mass 4 kg and length 500 mm, is hinged at the left hand side and supported at rest by a chain (S) attached 10 cm from the hinge. Calculate the magnitude and direction of the reaction force on the rod at the hinge. State the principle you have...
  14. F

    Finding magnitude and direction of an electric field

    Homework Statement A spaceship encounters a single plane of charged particles, with the charge per unit area equal to σ. The electric field a short distance above the plane has magnitude _____ and is directed _____ to the plane. a) σ/2∈0, parallel b) σ/2∈0, perpendicular c) σ/∈0, parallel...
  15. jlmccart03

    Finding magnitude and direction of net force on a dipole.

    Homework Statement A dipole with charges ±q and separation 2a is located a distance x from a point charge +Q, oriented as shown in the figure. Part A: Find an expression for the magnitude of the net force on the dipole in the limit x≫a. Part B: What is the direction of the net force...
  16. J

    Magnitude & Direction of Resultant Force & Equilibrant Force

    Homework Statement I need help as to how to find the magnitude and direction of the resultant force, and the equilibrant force. Any and all help is greatly appreciate as I'm stressing myself out over it and I'm not sure what to do. Thanks, Jamie. Homework Equations First question...
  17. J

    Magnitude and DIRECTION of electric field of a square.

    Homework Statement Calculate the magnitude of the electric field at the center of a square 42.5cm on a side if one corner is occupied by a −38.2μC charge and the other three are occupied by −26.9μC charges. (This part done) Choose the correct direction of the electric field at the center of...
  18. Alistair McCheyne

    Slider Crank Magnitude and Direction of Force on Member AB

    Homework Statement Homework Equations The Attempt at a Solution https://scontent-lhr3-1.xx.fbcdn.net/v/t34.0-12/13140955_10156888508510486_863100825_n.jpg?oh=3f13a038f3dc053c7a10858aa62f6fc0&oe=57318819...
  19. Alistair McCheyne

    Slider Crank Mechanism Magnitude and Direction

    https://scontent-lhr3-1.xx.fbcdn.net/v/t34.0-12/13181084_10156883800920486_1357045350_n.jpg?oh=a39d7777f01c4aa06301c4f3d740de1e&oe=57301DBC Hi I am currently studying design engineering and my lecturer has left just before an exam. I really don't know how to find the magnitude and direction of...
  20. R

    Magnitude and Direction of induced voltage

    Homework Statement Hey everyone I have a physics e&m question: [/B] http://blob:https%3A//www.physicsforums.com/aa779f37-be23-43d7-a888-d70263a3854b Homework EquationsThe Attempt at a Solution I took the derivative to find the magnitude of the induced voltage. (do I need to add a constant...
  21. B

    Force magnitude and direction Problems

    Homework Statement When doing force problems, you're sometimes asked to solve for the magnitude and direction of a given force acting on an object given the mass of the object, its accelleration, and the other forces acting on it. However, the force that you need to solve for could be...
  22. C

    Finding the magnitude and direction of the electric field

    Homework Statement 13. Find the magnitude and direction of the electric field at P due to the two charges shown. Homework EquationsThe Attempt at a Solution I have attached both the question, which involves a diagram, as well as my attempt at the answer below. My first question is regarding...
  23. B

    Find the magnitude and direction of vectorA - vector B?

    Homework Statement Vector A⃗ has a magnitude of 20m and makes an angle of 30∘ above the positive x axis. Vector B⃗ has a magnitude of15m and is oriented 60∘ to the left of the y axis. Find the magnitude of A⃗ −B⃗ . Find the direction of A⃗ −B⃗ . Homework Equations sin 150 = sin 30 = 0.5 cos...
  24. S

    Find the magnitude and direction of the acceleration of the

    Homework Statement m=25 kg, F1=88N[E55N],F2=54N[E], mu (coefficient of friction) = 0.350 Homework Equations FNet=F1+f2-Ff The Attempt at a Solution 88cos55 + 54=104.47, 88sin55+0=72.1. dheta=tan inverse (72.1/104.47)=34.6 degrees, what direction is Ff is my question and I would appreciate a...
  25. SadPanda6022

    What is the magnitude and direction of resulting force with given values?

    I attached problem. I got F1 = 2.7x10-8 and F2 = 8.3x10-9 sqrt(f1^2 +f2^2) = 2.818x10^-8 theta was inverse tan of f1/f2. got 72.8 please help :(
  26. A

    Magnitude and direction of acceleration

    Homework Statement A car with a mass of 1.3x10^4kg is initially moving at 35 km/hr in a straight line when the car comes to a complete stop at 15m. What is the magnitude and direction of acceleration?b) the magnitude and direction of the breaking force c) thetime required to stop Homework...
  27. Calpalned

    Dipole magnitude and direction (21.67)

    Homework Statement Homework Equations Total electric field = Electric field caused by Q_1 + electric field caused by Q_2 ##\vec{e} = \vec{e_1}+\vec{e_2}## Dipole moment = ##P = Ql## The Attempt at a Solution **For Part A** ##\vec{E} = \vec{E_1}+\vec{E_2}## The charges are opposite so it...
  28. moenste

    Mechanics. Vectors. Find magnitude and direction of forces

    Homework Statement Find the magnitude and direction of the resultant of the following pair of forces: 60 N at 150 degrees to 20 N Answer: 43.8 N at 136.7 degrees to 20 N and 13.3 degrees to 60 N Homework Equations Cosine and sine rules: R2 = a2 + b2 - 2 * a * b * cos A a / sin A = b / sin b =...
  29. gracy

    Understanding Torque: Magnitude and Direction

    As we know all vectors with the same magnitude and direction are equal despite their different locations.so we can move the force vector such that Now how will it produce torque?Please tell me where am i getting wrong?
  30. A

    Physics magnitude and direction?

    I know this is basic stuff, but if anyone would be willing to help... :) At a certain time, a car is 150 meters due west of your house. If it is traveling with a constant velocity of 30m/s 30 degrees south of east, what are the ,magnitude and the direction of its position relative to your house...
  31. S

    Magnitude and Direction of an (E) Electric field of a square

    Homework Statement What is E in Magnitude and Direction at the center of the square of (fig. 3-7). Assume that q = 10x10-8 C and a = 5 cm Now I have am not well versed with vectors, I don't like them and they don't like me. I can not figure out the directions the magnitudes move in.Homework...
  32. Brendan Webb

    Finding the Magnitude and Direction of the Displacement Vector for a Ship's Trip

    A ship sails 130 km due north from island A to island B and then 92 km, in the direction 22° south of east, to island C. The ship after that returns directly to island A. Calculate the magnitude and direction of the displacement vector in the last trip. Draw appropriate diagrams. Homework...
  33. I

    How to get the magnitude and direction?

    A bomb is released from an airplane flying horizontally at an elevation 1600 ft with a velocity of 294 ft/s. I don't know how to get the magnitude. Will you please help me?
  34. R

    Effect of Magnitude & Direction on Organpipe's Note

    I am reading "Relativity: The Special and General Theory" by Albert Einstein, and in orden to continue reading with full understanding, I would like someone to please clarify one thing for me (or most likely more than one). In the section dealing with "The Principle of Relativity (in the...
  35. H

    Determine the magnitude and direction of the effective value of g

    Homework Statement [/B] Determine the magnitude and direction of the effective value of g at a latitude of 45 degrees on the Earth. Assume the Earth is a rotating sphere. Homework Equations a = v2/r The Attempt at a Solution This question requires a vector diagram no doubt. What I know is...
  36. J

    Velocity (Magnitude and Direction) of a tossed object as it hits something

    Homework Statement John jumps and shoots and makes a basket from the far end of the court, a distance of 27.5 m. The ball is shot at an angle of 41.0 degrees to the horizontal from a height of 1.98 m above the ground with a speed of 17.2 m/s. The basket is 3.00 m off the ground. a. Sketch a y...
  37. O

    Electric Fields: Magnitude and Direction.

    Homework Statement Calculate the magnitude and direction of the electric field at point Z in Figure 13, due to the charged spheres at points X and Y. Homework Equations E = kq1/r^2 The Attempt at a Solution Determine each vector component: Ex = (9.0x10^9 Nm^2/C^2)(50.0 x...
  38. I

    Determine the magnitude and direction of forces

    Homework Statement The figure shows a frame with a 100N object hanging on it. Determine the magnitude and direction of forces exerted on AB and BC respectively. Homework Equations ∑Fx=0, ∑Fy=0, ∑M=0 The Attempt at a Solution I believe this question is unsolvable. The free body...
  39. V

    Magnitude and direction of Electric field

    Homework Statement Calculate the magnitude of the electric field E = (-11i^+14j^)N/C ∣∣E⃗ ∣∣ = _______ N/C Calculate the direction (relative to the +x-axis ) of the electric field E = (-11i^+14j^)N/C. θ =_________∘ counterclockwise from the +x-axis Homework Equations...
  40. B

    Finding the magnitude and direction

    Homework Statement A 325Kg boat is sailing 15° north of east at a speed of 2.00ms-1. Thirty seconds later it is sailing 35° north of east at a speed of 4.00ms-1. During this time, three forces act on the boat: A 31N force directed 15° north of east (engine), a 23N force directed 15° south of...
  41. anthonyk2013

    Getting magnitude and direction of 3 forces

    I have completed this question but I am not sure I am right. 3 co-planer forces acting at a point 0, 100KN→ at 0deg from o point, 70KN→120deg from o point and 50KN →210deg from o point (hope that make sense, can't draw it). using a scale of 10mm+10KN determine, By means of polygon of...
  42. V

    Magnitude and direction of an electric field outside of a plate?

    Homework Statement A circular metal plate of radius 0.2 m has 1010 excess electrons uniformly distributed over its surfaces. What is the magnitude and direction of the field just outside the plate near its center? Homework Equations E = kQ/r2 The Attempt at a Solution Starting with E =...
  43. C

    Magnitude and direction of electric field with nonconducting sheets

    Homework Statement Two very large, non-conducting sheets, each 10cm thick, carry uniform charge densities δ1 = -6.00μC/m^2, δ2 = +5.00μC/m^2, δ3 = +2.00μC/m^2, δ4 = 4.00μC/m^2. Use Gauss's law to find the magnitude and direction of the electric field at points A, B, and C, far from the edges...
  44. M

    How Do You Calculate Vector Addition and Subtraction?

    Homework Statement Vector a has a magnitude of 4.3 m and is directed east. Vector b has a magnitude of 3.9 m and is directed 35° west of north. What are (a) the magnitude and (b) the direction (from east) of a + b ? What are (c) the magnitude and (d) the direction (from east) of b - a...
  45. S

    Magnitude and Direction of Electric Point Charges

    1. 1: Suppose eight identical point charges q are placed at the corners of a cube with side length L. Find the magnitude and direction of the electric force produced exerted by these charges on another charge q at the center of a face of the cube. Homework Equations 3. So far...
  46. S

    Magnitude and Direction of Electric Fields

    Hey yall. This is a question from my homework but it's so basic that it's just to help with the concept for me. So the question is this: A small object A, electrically charged, creates an electric field. At a point P located 0.250 directly north of A, the field has a value of 40.0 directed to...
  47. P

    Finding the Magnitude and Direction of Magnetic Field of 2 parallel wi

    Homework Statement Two long, parallel wires carry currents of I1 = 2.78 A and I2 = 4.80 A in the direction indicated in the figure below. (Choose the line running from wire 1 to wire 2 as the positive x-direction and the line running upward as the positive y-direction.) a) Find the magnitude...
  48. T

    Finding the magnitude and direction in a electric field.

    Three point charges are placed at the vertices of an equilateral triangle (of side .2m). The triangle is setup on an X-Y plain. On the top of the triangle on the Y-axis the charge is q7= -7μC, the positive X-axis the charge is q3= 3μC, and on the -X-axis the charge is q2= 2μC. Part A). What...
  49. I

    Finding magnitude and direction of net torque on a dipole

    Homework Statement For the dipole shown, the charges are ± 3.0 micro coulombs separated by a distance of 3.20 nm and oriented so that the theta is 35.0 degrees. If the electric field has a magnitude of 8000 N/C, find the magnitude and direction (clockwise/counterclockwise) of the net torque...
  50. B

    Magnitude and direction of Vectors using head to tail rule

    Homework Statement Homework Equations F = \sqrt{F_x^2 + F_y^2} tan\theta = F_y / F_x The Attempt at a Solution Page 1 : http://i49.tinypic.com/vfw74k.jpg Page 2 : http://i50.tinypic.com/2qspamr.jpg Page 3 : http://i49.tinypic.com/24zgl6x.jpg is it correct?
Back
Top