Question

1. 2. A proton moving with a speed of 6.0 x 10^m/s in the +x-direction enters a uniform magnetic field of 0.50 T directed in the +z-direction. What is the magnetic force exerted by the magnetic field on the electron? A. -(2.4 x 10-15 N)j B. (2.4 x 10-N)j C. -(4.8 x 10-15 N)j D. (4.8 x 10-15 N)j A proton moving with a speed of 6.0 x 10*m/s in the +x-direction enters a uniform magnetic field of 0.50 T directed in the +z-direction. What is the radius of the proton's circular motion? A. 1.52 x 10-m B. 1.25 x 10 m C. 6.83 x 10-7m D. 6.38 x 10-7 m A straight conductor carrying a current of 20 A eastward is placed in a uniform magnetic field of 0.50 T, 60° NW. What is the direction of the magnetic force on a 10-cm segment of the conductor? A. 0.50 N, downward B. 0.50 N, upward C. 0.87 N, downward D. 0.87 N, upward 3.

WRITE THE LETTER OF THE CORRECT ANSWER. IF THERE IS NO CORRECT ANSWER, WRITE "E".

Answer 1

1.

Force on a charge moving in magnetic field is given by:

F = q*VxB

F = 1.6*10^-19*(6.0*10^4 i)x(0.50 k)

F = 1.6*10^-19*6.0*10^4*0.50*(ixk)

F = 4.8*10^-15 (-j) N

Correct option is C.

2.

Using force balance on charge moving in magnetic field

Fc = Fm

m*V^2/R = q*V*B

R = m*V/(q*B)

R = 1.67*10^-27*6.0*10^4/(1.6*10^-19*0.50)

R = 1.25*10^-3 m

Correct option is B.

3.

Force on a current carrying wire in magnetic field is given by:

F = i*LxB

I = 20 A eastward = (20 i) Amp

B = 0.50 T, 60 deg NW = (-0.50*cos 60 deg i + 0.50*sin 60 deg j)

L = length of segment = 10 cm = 0.1 m

So,

F = 0.1 m*(20 i)x(-0.50*cos 60 deg i + 0.50*sin 60 deg j)

In cross-product, ixi = 0 and ixj = k

So,

F = 0 + 0.1*20*0.50*sin 60 deg*(ixj)

F = (0.87 k) N = 0.87 N upward

Correct option is D.

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