PAST-QUESTION PHY112 ( PHYSICS112 CODE: PHY 112 COURSE TITLE: ELECTRICITY, MAGNETISM AND MODERN PHYSICS COURSE)

phys112

PAST-QUESTIONS

 CODE: PHY 112
COURSE TITLE: ELECTRICITY, MAGNETISM AND MODERN PHYSICS COURSE

1.  
Tesla is a unit of

A. Field strength

B. Inductance

C. Flux density

D. Flux

ANS= C

2.   A magnetic
field exists around

A. Iron

B. Copper

C. Aluminum

D. Moving charges

ANS= D

3.  
The direction of magnetic lines
of force is:

A. from south pole to north pole

B. from north pole to south pole

C. from one end of the magnet
to another

D. none of the above

ANS= B

4.   The ratio of permittivity of a material
to that of free space is known as:

A. relative permittivity

B. susceptibility

C. flux density

D. relative permeability

ANS= A

5.   The most effective and quickest way of making
a magnet from soft iron is by:

A. placing it inside a coil carrying
current

B. induction

C. the use of permanent
magnet

D. rubbing with another magnet

ANS= D

6.   Two equal and opposite
charges are placed 40mm apart. If the force between
them is 0.5N, calculate the magnitude of the charge
(Assume 1 4𝜋𝜀0= 9.0 × 109𝑁𝑚2𝑐2).

A. 2.98 ×
10−13𝐶

B. 2.98 ×
10−15𝐶

C. 2.98 ×
10−14𝐶

D. 2.98 ×
10−12𝐶

ANS= A

7.   Determine the area of the parallel
plate capacitor in the air if the capacitance is 25 × 10−9𝐹 and the

separation between the plates is 0.04𝑚. (𝐴𝑠𝑠𝑢𝑚𝑒 𝜀0 = 8.854 × 1012 𝑓
𝑚⁄ )

A. 122.94𝑚2

B. 114.94𝑚2

C.
113.94𝑚2

D. 112.94𝑚2

ANS= D

8.   A metal
is illuminated with light of energy 4.4 × 10−19𝐽. If the work function of the metal
is 3.04 ×10−19𝐽. Calculate the threshold wavelength. (𝐴𝑠𝑠𝑢𝑚𝑒 ◻ = 6.6 × 10−34𝐽𝑆, 𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦 𝑜𝑓 𝑙𝑖𝑔𝑡 =3.0 × 108𝑚/𝑠).

A. 6.5 × 10−7𝑚 B. 6.8 × 10−8𝑚

C.6.5
× 10−9𝑚

D.6.8
× 10−7𝑚

ANS= C

9.   A 0.4nm diameter copper wire carries
a current of 3μA. Find the current
density

A. 89.23Am-2

B. 23.89Am-2

C. 38.29Am-2

D. 93.28Am-2

ANS= B

10.  Calculate the e.m.f induced
in a coil of 200turns
placed in a field were the rate of change of flux is

0.01wbs-1

A. -12V B.-0.12V

C. –1.2V

D. –2.0V

ANS= D

11.  The law which states
that “the direction of the induced
e.m.f is such that it tends to oppose the change

that produces
it” is associated with

A. Maxwell’s law

B. Faraday’s law

C. Lenz’s law

D. Gauss’s law

ANS= C

12.   A 20mH inductor is connected in series with a 6μF capacitor. What is the angular
frequency of the

circuit

A. 9132.4rad/s

B. 3219.42rad/s

C. 9321rad/s

D. 9421.32rad/s

ANS= C

13.   Calculate the binding energy for 2311Na Take ( Atomic mass = 22.98977iu , mass of proton =

1.007825u , mass of neutron = 1.008665u u=931mev)

A. 186.5Mev

B. 168.5Mev

C. 185.6Mev

D.
156.8Mev

ANS= C

14.   The minimum
energy needed to eject an electron from a metal surface is called

A. Work function

B. Threshold frequency

C. Threshold wavelength

D. Radiation intensity

ANS= A

15.   There resistors 2 Ω , 6 Ω and 9 Ω are connected in parallel. Calculate the equivalent resistance

A. 2.3Ω

B. 1.3 Ω

C. 1.0 Ω

D. 17.0 Ω

ANS= B

16.   What is the S.I. Unit of charge?

A. Ohms

B. Coulombs

C. Farads

D. Newtons

ANS= B

17.   Continuous flow of charge
can be generated from the following except

A. Photo cells

B. Thermoelectricity

C. A.C. generator

D. Radio waves

ANS= D

18.   Which of the following is not a method of demagnetization?

A. Double touch

B. Heating

C. Hitting the magnet

D. Thermal agitation

19.   A transformer with 220V input and 12V output is a … transformer.

A. Step up

B. Normal

C. Step down

D. Power

ANS= C

20.   The overall
resistance of A R-L-C Series
circuit is called

A. Inductor

B. Capacitance

C Impedance

D. Voltage

ANS= B

21.   Current in a 60 W light bulb when it is connected to a 230 V power supply is

A. 0.26 A

B. 1.5 A

C. 2.6 A

D. 3.9 A

ANS= A

22.   Magnitude of induced e.m.f is proportional to

A. rate of change of current

B. rate of change of voltage

C. rate of change of magnetic flux linkage

D. rate of change of resistance

ANS= C

23.   When lightning strikes a lightning rod on top of a tall building, electrical energy flows through a wire

and
into the           

A. cloud

B. ground

C. roof

D. Atmosphere

ANS= B

24.   If the resistivity of a wire is 4 x 107 m, the resistances of a pieces
of wire of length 20m and

cross sectional
area 8 x 10-6 M2 is

A. 1.0

B. 10.0

C. 0. 5

D. 5.0

25.   Calculate the power delivered by a 3-phase
line, if its voltage and current are 120V and 60A

respectively.

A. 20kw

B. 7.2kw

C. 2.4kw

D. 0.2kw

ANS= B

26.   Capacitor is fully charged
if potential difference is equal to

A. e.m.f

B. current

C. resistance

D. power

ANS= A

27.   A capacitor
has capacitance of 2μF. Find the capacitive reactance if a frequency of 50Hz
and 220V

a.c voltage
are applied?