WAEC Past Questions and Answers - Page 3271

16,351.

Six dry cells each of e.m.f. 2.0 and internal resistance of 1.0\(\Omega\) are connected in parallel across a load of 3.0\(\Omega\). Calculate the effective current in the circuit.

A.

0.63A

B.

0.50A

C.

0.31A

D.

0.22A

Correct answer is A

I = \(\frac{f}{n} = \frac{1}{6 - 2}\)

I = \(\frac{v}{R + r} = \frac{2}{3} + \frac{1}{6} = 0.63\)A

16,352.

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.

16,353.

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

16,354.

When depreciation is deducted from Gross National Product, the result is

A.

Total national income

B.

Gross domestic product

C.

Net national product

D.

Net domestic produc

Correct answer is C

Net national product is the total value of goods produced and services provided in a country during one year, after depreciation of capital goods has been deducted.

16,355.

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.