Q: If the direction of the electric field $\vec{E}$ and magnetic field $\vec{B}$ of an electromagnetic wave are given, what is the direction of propagation of the wave?

In the direction of $\vec{E} \times \vec{B}$

Q: What is the formula for the critical angle $\theta_c$ for total internal reflection when light passes from medium 1 ($n_1$) to medium 2 ($n_2$)?

$\sin \theta_c = \dfrac{n_2}{n_1}$

Question 1

A very long straight wire carries a uniform linear charge density $\lambda$. What is the expression for the electric field $E$ at a distance $r$ from the wire?

Accepted Answer

$E = \dfrac{\lambda}{2\pi\epsilon_0 r}$

Question 2

If the electric field $E$ between two parallel plates is halved, what happens to the surface charge density $\sigma$ on the plates?

Accepted Answer

$\sigma$ is halved

Question 3

A wire of length $L$ and resistivity $\rho$ has a resistance $R$. If the diameter of the wire is doubled, what happens to the resistance?

Accepted Answer

Resistance becomes one-fourth of the original value

Question 4

Three resistors $R_1$, $R_2$, and $R_3$ are connected in series. What is the total resistance $R_s$?

Accepted Answer

$R_s = R_1 + R_2 + R_3$

Question 5

A parallel plate capacitor is connected to a battery. If a dielectric is inserted between the plates, what happens to the voltage $V$ and the electric field $E$ across the plates?

Accepted Answer

Voltage remains the same, electric field decreases

Question 6

Two long parallel wires carry equal currents in opposite directions. Where is the magnetic field between the wires zero?

Accepted Answer

At a point between the wires, equidistant from both

Question 7

A solenoid has a radius $r$ and carries a current $I$. If the magnetic field $B$ and the electric field $E$ at a distance from the axis are known, how can you find the radius of the solenoid?

Accepted Answer

By using the relationship between $E$, $B$, and $r$ specific to the solenoid's geometry

Question 8

The energy density $u$ in a magnetic field is given by which formula?

Accepted Answer

$u = \dfrac{B^2}{2\mu_0}$

Question 9

A long straight wire carries a current $I$. What is the magnetic field $B$ at a distance $r$ from the wire?

Accepted Answer

$B = \dfrac{\mu_0 I}{2\pi r}$

Question 10

According to Faraday's law, what is the induced emf $\epsilon$ in a coil with inductance $L$ when the current changes at a rate $\dfrac{di}{dt}$?

Accepted Answer

$\epsilon = -L \dfrac{di}{dt}$

Question 11

Which statement about electromagnetic waves is correct?

Accepted Answer

They are transverse waves and do not require a medium to propagate

Question 12

In the electromagnetic spectrum, which type of wave has the highest frequency?

Accepted Answer

Gamma rays

Question 13

If the direction of the electric field $\vec{E}$ and magnetic field $\vec{B}$ of an electromagnetic wave are given, what is the direction of propagation of the wave?

Accepted Answer

In the direction of $\vec{E} 	imes \vec{B}$

Question 14

An electromagnetic wave is propagating in the $+x$ direction. If the electric field is $E = 0.2 \sin(kx - \omega t)$ V/m, what is the magnitude of the Poynting vector $S$?

Accepted Answer

$S = \dfrac{E^2}{\mu_0 c}$

Question 15

If the index of refraction of a material is $n$, what is the speed of light $v$ in that material?

Accepted Answer

$v = \dfrac{c}{n}$

Question 16

When a ray passes from air ($n_1 = 1$) into glass ($n_2 = 1.5$), which statement is true about the angle of refraction $	heta_2$ compared to the angle of incidence $	heta_1$?

Accepted Answer

$	heta_2 < 	heta_1$

Question 17

Total internal reflection occurs only when light travels from a medium with index $n_1$ to a medium with index $n_2$ such that:

Accepted Answer

$n_1 > n_2$

Question 18

What is the formula for the critical angle $	heta_c$ for total internal reflection when light passes from medium 1 ($n_1$) to medium 2 ($n_2$)?

Accepted Answer

$\sin 	heta_c = \dfrac{n_2}{n_1}$

Question 19

A wire of length $L$ and area $A$ has resistance $R$. If the resistivity is $\rho$, what is the correct formula for $R$?

Accepted Answer

$R = \dfrac{\rho L}{A}$

Comprehensive Physics Review: Electricity, Magnetism, and Electromagnetic Waves

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