Physics questions and answers

Physics Questions and Answers

If you want to learn more about the nature and properties of matter and energy or you're simply preparing for a Physics exam, these Physics past questions and answers are ideal for you.

3,656.

In the diagram above, a 200 W bulb is lighted by a 240 V a.c mains supply. If 1kwh is sold at N40, the cost of keeping the bulb lighted for a day is?

A.

N1,920.00

B.

N192.00

C.

N19.20

D.

N1.92

Correct answer is B

Energy consumed = power x time
= 200W x 24hr = 4800wh
= 4.8 kwh
But 1 kwh cost N40
∴ 4.8kwh costs 4.8 x 40
= N192

3,657.

Three 4Ω resistors connected in parallel have a potential difference of 16 V applied across them. What is the total current in the circuit?

A.

14 A

B.

12 A

C.

10 A

D.

8 A

Correct answer is B

1/R = 1/4 + 1/4 + 1/4 = 3/4
R = 4/3
I = V/R

= 16
4/3

= 16 x 3
_4

= 12 A

3,658.

The diagram above shows a balanced metre bridge, the value of x is

A.

75.0 cm

B.

66.7 cm

C.

33.3 cm

D.

25.0 cm

Correct answer is C

1/R = 1/8 + 1/8 = 2/8
∴ R = 4Ω
l/l1 = R/R1
(x)/(100-x) = 4/8
4(100-x) = 8x
400-4x = 8x
400 = 8x + 4x = 12x
x = 400/12 = 33.3cm

3,660.

Three capacitors of capacitance 2μF, 4μFand 8μF are connected in parallel and a P.D of 6V is maintained across each capacitor, the total energy stored is?

A.

2.52 x 10-6J

B.

6.90 x 10-6J

C.

2.52 x 10-4J

D.

6.90 x 10-4J

Correct answer is C

C = C1 + C2 + C3
= 2 + 4 + 8 = 14μF
V = 6V
Energy = 1/2CV2
1/2 x 14 x 10-6 x 62
= 2.52 x 10-4 J