Electricity and Magnetism Answers

on cathode ray oscilloscope,the distance between crests is 2cm.if the time base is set at 10ms/cm.what is the period of the wave

An electron beam passes un deflected with

uniform velocity v through two parallel

plates, when a magnetic field of 0 01 T is

applied perpendicular to an electric field

between the plates produced by a p d of

100 V The separation of the plates is 5 mm

Calculate the velocity?

Briefly explain the motor effect, including the direction of deflection (motion). Your response should include five main points about the motor effect.

An AM radio antenna pi

ks up a 1000 kHz signal with a peak voltage of 5.0 mV. The tuning

ir

uit


onsists of a 60 µH indu

tor in series with a variable

apa

itor. The indu

tor

oil has a resistan

e of

0.25 Ω, and the resistan

e of the rest of the

ir

uit is negligible.

(a) To what value should the

apa

itor be tuned to listen to this radio station? (Note that the


apa

itor needs to be tuned to where it is in resonan

e with the indu

tor).

(b) Cal

ulate the peak

urrent through the

ir

uit at resonan

e.

(

) A stronger station at 1050 kHz produ

es 10 mV antenna signal. Cal

ulate the

urrent at this

frequen

y and the

orresponding phase angle when the radio is tuned to 1000 kHz.

A at

oil of wire has an area A, N turns, and a resistan

e R. It is situated in a magneti

eld,

su

h that the normal to the

oil is parallel to the magneti

eld. The

oil is then rotated through

an angle of φ = 90◦

, so that the normal be

omes perpendi

ular to the magneti

eld. The

oil has

an area of 1.5 × 10−3 m2

, 50 turns, and a resistan

e of 140 Ω. During the time while it is rotating, a


harge of 8.5 × 10−5 C ows in the

oil. Cal

ulate the magnitude of the magneti

eld?

(a) Two parallel, very long wires 1 and 2 are separated by a distan

e of 0.065 m and

arry

urrents

of I1 = 15 A and I2 = 7 A. Find the magnitude of the for

e that the magneti

eld that wire 1

applies to a 1.5 m of wire 2 when the

urrents are in opposite dire

tion.

(b) A 150-turn solenoid

arries a

urrent of 12 A. The radius of the solenoid is 0.050 m; and its length

is 0.18 m. Determine the magneti

ux through the

ir

ular

ross-se

tional area at the

enter of

the solenoid.

The drawing below shows an ele

tri



ir

uit, where resistors are

onne

ted to a battery. If the

urrent

in the 8.0 Ω resistor is 0.5 A,

al

ulate:

(a) the equivalent resistan

e,

(b) the

urrent in ea

h resistor,

(

) the total

urrent owing in the

ir

uit,

(d) the voltage of the battery,

(e) the ele

tri

power of the

ir

uit.

We have an infinite, non conducting, sheet of negligible thicknress carrying a negative uniform surface charge density  and, next to it, an infinite parallel slab of thickness D with positive uniform volume charge density  (see sketch). All charges are fixed. Calculate the direction and the magnitude of the electric field.

(a) Above the negatively charged sheet.

(b) In the slab

(c) Below the slab

(d) Make a plot of E as a function of distance, z, from the sheet.

A charged sphere of mass 0.62 kg and net charge 0.34 µC hangs at rest at the end of an insulating string above a large sheet of charge. The horizontal sheet of uniform charge creates a uniform vertical electric field in the vicinity of the point charge. The tension in the string is measured to be 5.67 N.

(a) In a free-body diagram, show the forces that act on the charged sphere.

(b) Calculate the magnitude and direction of the electric field due to the sheet of charge.

Positive charge Q is distributed uniformly along the positive y-axis between y = 0 and y = a. A point P lies on the positive x-axis, a distance x from the origin (see figure)

(a) Calculate the x and y-components of the electric field produced by the charge distribution Q at points on the positive x-axis.

(b) Show that if x≫a

E_x ≅Q/(4πε_0 x^2 )

E_y ≅- Qa/(8πε_0 x^3 )

Explain why this result is obtained