WAEC Physics Past Questions & Answers - Page 91

451.

Which of the following properties is an advantage of lead-acid accumulator over an alkaline accumulator?

A.

possesses low internal resistance

B.

can be recharges

C.

has shorter life span

D.

possesses high e.m.f

Correct answer is D

No explanation has been provided for this answer.

452.

Two capacitors, each of capacitance 2\(\mu\)F are connected in parallel. If the p.d across them is 120V, calculate the charge on each capacitor

A.

6.0 x 10-5C

B.

1.2 x 10-4C

C.

2.4 x 10-4C

D.

4.8 x 10-4C

Correct answer is C

C = \(C_1 + C_2 = 2 + 2 = 4 \mu F\)

but Q = CV

= 4 x 10\(^{-6}\) x 120

= 4.8 x 10\(^{-4}\)

\(\therefore\) Each of the capacitor has a charge of \(\frac{4.8 \times 10^{-4}}{2}\)

= 2.4 x 10\(^{-4}\) C

453.

When two like charges are brought together, the potential energy of the system formed will

A.

increase because work is done against the field

B.

increase because work is done by the field

C.

decrease because work is done by the field

D.

decrease because work is done against the field

Correct answer is A

if two like charges are close together, they repel each other. moving them closer together requires working against repulsive force which increases the potential energy of the system.

454.

Which of the following sets of coloured light is/are secondary colours i. Red, Blue and green ii. Blue, cyan and magneta iii. Green, Magenta and yellow, IV Yellow, Cyan and Magenta

A.

i and ii only

B.

ii and iii only

C.

iv only

D.

i, ii and iv only

Correct answer is C

No explanation has been provided for this answer.

455.

The sound heard by a person after the reflection of the sound generated by him is called

A.

reverberation

B.

resonance

C.

echo

D.

audibility

Correct answer is C

No explanation has been provided for this answer.