Electricity and Magnetism Answers

hat is the change in the potential energy of the system comprising the plates and the electron when the electron moves from the negative plate to the positive plate?

what is a

1. Two charges are 60cm apart, in air. One charge Q1 is +1.67 x 10^-7C; The other Q2 is

-1.67 x 10^-7 C. What is the electric field intensity at P midway between the charges?

2. The average distance between the electron and the proton in a certain atom is 5 x 10^-10m. How strong is the electric field that the proton experiences?

3. Two charges Q1 = 2.3 x 10-9C and Q2 = 3.5 x 10-9C, are 55mm apart. What is the electric field halfway between them?

4. Two charges of 6uC are 2.5m apart. Where is the electric field along the line joining them equal to zero?

5. What is the electric field at one vertex of an equilateral triangle whose sides are 10cm long if there are charges of -30uC at the other vertexes?

Explain: Can the force caused by an electric field be greater than the force due to a gravitational field? Give an example to prove this.

A small source of sound waves emits uniformly in all directions. The total power output of the source is P. By what factor must P increase if the sound intensity level at a distance of 20.0 m from the source is to increase 5.00 dB?

1. A coil with 25 turns of wire is wrapped around a hollow tube with an area of 1.8 m². Each turn has the same area as the tube. A uniform magnetic field is applied at a right angle to the plane of the coil. If the field increases uniformly from 0.00 T to 0.55 T in 0.85 s, find the magnitude of the induced emf in the coil. If the resistance in the coil is 2.5 , find the magnitude of the induced current in the coil.

2. A coil consists of 200 turns of wire having a total resistance of 2.0. Each turn is a square of side 18 cm, and a uniform magnetic field directed perpendicular to the plane of the coil is turned on. If the field changes linearly from 0 to 0.50 Tin 0.80 s, what is the magnitude of the induced emf in the coil while the field is changing? What is the magnitude of the induced current in the coil while the field is changing?

Three charged particles are placed at the corners of an equilateral triangle of side 1.2

m. The charges are +4 μC, -8 μC, and -6 μC. Calculate the magnitude and direction of

the net force on each due to the other two.

Using Snell’s law, determine the constant when the angle of incidence and the angle of refraction are:

a) 50˚ and 30˚

b) 30˚ and 18˚

c) 60˚ and 38˚

1. An underwater swimmer looks up toward the surface of the water on a line of sight that makes an angle of 25˚ with a normal to the surface of the water. What is the angle of incidence in air for the light rays that enter the swimmer’s eye?

2. In each of the following questions, the second medium is air.

a) What is the critical angle if the index of refraction for a medium is 1.68?

b) What is the index of refraction of a medium if the critical angle is 40˚?

1. Light travels from air into water. If the angle of refraction is 30˚, what is the angle of incidence?

2. A ray of light in air strikes a block of quartz at an angle of incidence of 30˚. The angle of refraction is 20˚. What is the index of refraction in quartz? 

1. Using Snell’s law, determine the constant when the angle of incidence and the angle of refraction are: a) 50˚ and 30˚ b) 30˚ and 18˚ c) 60˚ and 38˚

2. a) What is the angle of refraction in a medium if the angle of incidence in air is 48˚ and the index of refraction of the medium is 1.58? b) What is the angle of incidence in a medium in the case where the angle of refraction in air is 40˚ and the index of refraction of the medium is 1.58?

3. A ray of light passes from air into water at an angle of incidence of 50˚. What is the angle of refraction? (HINT: You will need to use the sin1 function on your calculator).

The current through a circuit, in which emf of a cell ε = 120V and internal

resistance r = 0.01Ω is connected with load R= 1000Ω, is: