physics MCQs

1

The study of electric charges at rest under the action of electric forces is known as:

A

Electrodynamics

B

Magnetism

C

Electrostatics

D

Current Electricity

2

Who first made the measurement of the force between electric charges in 1874 AD?

A

Michael Faraday

B

Isaac Newton

C

James Clerk Maxwell

D

Charles Coulomb

3

Coulomb's law states that the force between two point charges is inversely proportional to:

A

the distance between them

B

the square of the distance between them

C

the product of the charges

D

the sum of the charges

4

The value of the proportionality constant k in Coulomb's law in SI units is:

A

9 x 10^9 Nm^2C^-2

B

8.85 x 10^-12 Nm^2C^-2

C

6.67 x 10^-11 Nm^2C^-2

D

1.6 x 10^-19 Nm^2C^-2

5

The permittivity of free space (ε₀) in SI units is given by:

A

9 x 10^9 C^2N^-1m^-2

B

8.85 x 10^-12 C^2N^-1m^-2

C

1 C^2N^-1m^-2

D

1.0006 C^2N^-1m^-2

6

If a dielectric medium is placed between two charges, the electrostatic force:

A

increases

B

decreases

C

remains unchanged

D

becomes zero

7

What is the value of relative permittivity (εᵣ) for a vacuum?

A

0

B

1.0006

C

1

D

Infinity

8

According to the text, which material has a relative permittivity value between 22-25?

A

Water

B

Air

C

Glass

D

Ammonia (liquid)

9

The concept of an electric field was introduced by:

A

Charles Coulomb

B

R.A. Millikan

C

Michael Faraday

D

Gauss

10

Electric field intensity is defined as the force per unit:

A

mass

B

length

C

charge

D

time

11

The SI unit for electric field intensity is:

A

Volt (V)

B

Newton per Coulomb (N/C)

C

Farad (F)

D

Joule (J)

12

The direction of the electric field intensity is the same as the direction of the force on a:

A

negative test charge

B

positive test charge

C

neutron

D

any charge

13

Electric field lines originate from charges and end on charges.

A

negative, positive

B

positive, negative

C

positive, positive

D

negative, negative

14

Where are the electric field lines closer together?

A

Where the field is weak

B

Where the field is uniform

C

Where the field is strong

D

Where there is no charge

15

Why can two electric field lines never cross each other?

A

Because they are parallel

B

Because electric field has only one direction at any given point

C

Because they are scalar quantities

D

Because they repel each other

16

In the region between two oppositely charged parallel plates, the electric field is generally:

A

zero

B

non-uniform

C

weak

D

uniform

17

What is the heart of a xerography (photocopier) machine?

A

A laser

B

An ink nozzle

C

A drum coated with selenium

D

Heated rollers

18

Selenium is a photoconductor, which means it is an insulator in the dark and becomes a conductor when exposed to:

A

heat

B

pressure

C

light

D

moisture

19

In an inkjet printer, which droplets are deflected into a gutter?

A

The uncharged droplets

B

All droplets

C

The charged droplets

D

The large droplets

20

The number of electric field lines passing through a certain element of area is known as:

A

Electric potential

B

Electric current

C

Electric flux

D

Electric power

21

The SI unit of electric flux is:

A

Nm^2C^-1

B

NC^-1

C

Vm

D

F/m

22

For maximum electric flux, the angle between the electric field E and the vector area A should be:

A

90°

B

45°

C

180°

D

0°

23

Gauss's law states that the total electric flux through a closed surface is equal to the total charge enclosed divided by:

A

4π

B

k

C

εᵣ

D

ε₀

24

What is the electric field intensity inside a hollow charged conducting sphere?

A

Infinite

B

Depends on the charge

C

Zero

D

Uniform

25

The electric field intensity due to an infinite sheet of charge is given by the formula:

A

E = σ / ε₀

B

E = σ / 2ε₀

C

E = 2σ / ε₀

D

E = q / ε₀

26

For a hollow charged metal sphere, the region inside the sphere is a:

A

high potential region

B

field-free region

C

low potential region

D

high-density charge region

27

The work done in bringing a unit positive charge from infinity to a point in an electric field is called:

A

Electric flux

B

Electric field intensity

C

Electric potential

D

Capacitance

28

The SI unit of electric potential is the:

A

Ampere

B

Coulomb

C

Joule

D

Volt

29

One volt is equivalent to:

A

One Joule per Coulomb

B

One Coulomb per Joule

C

One Newton per Coulomb

D

One Coulomb per second

30

The change in potential energy per unit charge between two points is known as:

A

Potential gradient

B

Potential difference

C

Electric force

D

Electric current

31

The relationship between electric field strength E and potential gradient is:

A

E = -ΔV / Δr

B

E = ΔV * Δr

C

E = Δr / ΔV

D

E = -Δr / ΔV

32

The electric potential due to a point charge q at a distance r is given by:

A

V = kq/r^2

B

V = kqr

C

V = kq/r

D

V = kq^2/r

33

One electron-volt (eV) is the energy acquired by an electron when it moves through a potential difference of one volt. Its value is:

A

1.6 x 10^-19 J

B

9.1 x 10^-31 J

C

1 J

D

1 V

34

Which force is much stronger and can be shielded?

A

Gravitational force

B

Nuclear force

C

Frictional force

D

Electrostatic force

35

In Millikan's oil drop experiment, an oil drop is suspended when the electric force is equal to the:

A

frictional force

B

viscous drag

C

gravitational force

D

upthrust

36

Millikan's experiment determined that electric charge is:

A

continuous

B

quantized

C

always positive

D

unmeasurable

37

A device used for storing electric charge is called a:

A

Resistor

B

Inductor

C

Transistor

D

Capacitor

38

The SI unit of capacitance is the:

A

Henry

B

Ohm

C

Farad

D

Volt

39

Capacitance is defined as the ratio of:

A

V/Q

B

Q/V

C

QV

D

W/Q

40

One farad is equal to:

A

One Volt per Coulomb

B

One Joule per Volt

C

One Coulomb per Volt

D

One Ampere per Volt

41

The capacitance of a parallel plate capacitor is directly proportional to:

A

the distance between the plates

B

the charge on the plates

C

the area of the plates

D

the voltage applied

42

Introducing a dielectric material between the plates of a capacitor will:

A

decrease its capacitance

B

increase its capacitance

C

not change its capacitance

D

make its capacitance zero

43

The ratio of the capacitance of a capacitor with a dielectric to its capacitance with a vacuum is called the:

A

permittivity

B

dielectric strength

C

dielectric constant

D

polarization

44

The phenomenon where the molecules of a dielectric form dipoles in an electric field is called:

A

Electric induction

B

Electric conduction

C

Electric polarization

D

Electric charging

45

Energy stored in a capacitor is given by the formula:

A

E = 1/2 C^2V

B

E = 1/2 CV

C

E = 1/2 CV^2

D

E = CV

46

The energy density in the electric field between capacitor plates is proportional to:

A

E

B

1/E

C

E^2

D

1/E^2

47

The time constant of an RC circuit is given by the product of:

A

R and V

B

C and V

C

R and C

D

R and Q

48

In a charging RC circuit, the time constant is the time required for the capacitor to store what percentage of its equilibrium charge?

A

100%

B

50%

C

63%

D

37%

49

In a photocopier, the black powder used to create the image is called:

A

selenium

B

toner

C

graphos

D

xeros

50

The electric potential at a point midway between two equal and opposite charges is:

A

doubled

B

halved

C