Q: If the wavelength of an electromagnetic wave is $600\ nm$, what is its frequency in vacuum? (Use $c = 3.0 \times 10^8\ m/s$)

$f = \frac{c}{\lambda} = \frac{3.0 \times 10^8}{600 \times 10^{-9}} = 5.0 \times 10^{14}\ Hz$

Question 1

Which of the following best describes the concept of 'dielectric strength' in a capacitor?

Accepted Answer

The maximum electric field a material can withstand without breakdown.

Question 2

A parallel plate capacitor is filled with a dielectric material of dielectric constant $k$. If the original capacitance without the dielectric is $C_0$, what is the new capacitance?

Accepted Answer

$C = k C_0$

Question 3

Which equation correctly relates electric potential energy ($U$) to charge ($q$) and electric potential ($V$)?

Accepted Answer

$U = qV$

Question 4

A charged particle is placed in a uniform electric field $E$. What is the magnitude of the force experienced by the particle?

Accepted Answer

$F = qE$

Question 5

Which of the following statements about equipotential lines is correct?

Accepted Answer

Equipotential lines are always perpendicular to electric field lines.

Question 6

A circuit contains a resistor of $10\ \Omega$ and a battery of $5\ V$. What is the current through the resistor according to Ohm's Law?

Accepted Answer

$I = \frac{V}{R} = \frac{5}{10} = 0.5\ A$

Question 7

Which of the following best describes 'resistivity'?

Accepted Answer

A property of a material that quantifies how strongly it resists current flow.

Question 8

A wire carries a conventional current of $2\ A$ for $5\ s$. How much charge passes through the wire in this time?

Accepted Answer

$Q = I t = 2 	imes 5 = 10\ C$

Question 9

Which of the following is true about direct current (DC) and alternating current (AC)?

Accepted Answer

DC flows in one direction only, while AC reverses direction periodically.

Question 10

A solenoid is used to create a magnetic field. Which equation gives the magnitude of the magnetic field inside a long solenoid?

Accepted Answer

$B = \mu_0 n I$

Question 11

A charged particle moves with velocity $\vec{v}$ perpendicular to a uniform magnetic field $\vec{B}$. What is the magnitude of the force on the particle?

Accepted Answer

$F = qvB$

Question 12

Which rule is used to determine the direction of the force on a moving charge in a magnetic field?

Accepted Answer

Right-hand rule

Question 13

Which of the following best describes electromagnetic waves?

Accepted Answer

Oscillations of electric and magnetic fields that propagate through space.

Question 14

The speed of light in vacuum is given by $c = \frac{1}{\sqrt{\mu_0 \epsilon_0}}$. What do $\mu_0$ and $\epsilon_0$ represent?

Accepted Answer

$\mu_0$ is the permeability of free space, $\epsilon_0$ is the permittivity of free space.

Question 15

If the wavelength of an electromagnetic wave is $600\ nm$, what is its frequency in vacuum? (Use $c = 3.0 	imes 10^8\ m/s$)

Accepted Answer

$f = \frac{c}{\lambda} = \frac{3.0 	imes 10^8}{600 	imes 10^{-9}} = 5.0 	imes 10^{14}\ Hz$

Question 16

Which of the following best describes the energy density ($u$) of an electromagnetic wave?

Accepted Answer

$u = \frac{1}{2} \epsilon_0 E^2 + \frac{1}{2} \frac{B^2}{\mu_0}$

Question 17

A point charge $q$ is located at a distance $r$ from another point charge $Q$. What is the electric potential at that point due to $Q$?

Accepted Answer

$V = \frac{Q}{4 \pi \epsilon_0 r}$

Question 18

A hospital uses an MRI machine that generates a strong uniform magnetic field. If a proton moves perpendicular to this field at $2 	imes 10^6\ m/s$ in a $1.5\ T$ field, what is the magnitude of the force on the proton? ($q = 1.6 	imes 10^{-19}\ C$)

Accepted Answer

$F = qvB = 1.6 	imes 10^{-19} 	imes 2 	imes 10^6 	imes 1.5 = 4.8 	imes 10^{-13}\ N$

Question 19

Which of the following is true about the relationship between electric field ($E$) and electric potential ($V$) in a uniform field?

Accepted Answer

$E = -\frac{dV}{dx}$

Physics Study Guide: Electric Potential, Current, Magnetism, and Electromagnetic Waves

Study Guide - Practice Questions

Study Guide - Flashcards