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WAEC Physics Past Questions & Answers - Page 47

231.

Which of the following pairs of concepts constitutes complementary variables as expressess by the Heinsberg uncertainty principle?

A.

Momentum and time

B.

Energy and acceleration

C.

Position and momentum

D.

Velocity and Momentum

Correct answer is C

No explanation has been provided for this answer.

232.

The opposition offered to an alternating current in a C-R series circuit is known as

A.

impedance

B.

resistance

C.

reactance

D.

friction

Correct answer is A

No explanation has been provided for this answer.

233.

The diagram above illustrates two charged bodies, X and Y separated by a distance r. Each body has charge q and mass m. Which of the following statements about the electrostatic force Fe and gravitational force Fg acting between the bodies is correct?

A.

Fe is attraction while Fg is repulsion

B.

Both Fe and Fg are that of repulsion

C.

Both Fe and Fg is that of attraction

D.

Fe is repulsion while Fg is attraction

Correct answer is D

 electrostatic force can be repulsive or attractive and gravitational force is only attractive. 

234.

The main reason why a.c. is transmitted at very high voltage and low current is that

A.

flows faster through the conductor

B.

can be stepped down

C.

is cheaper to generate

D.

reduces heat loss

Correct answer is D

No explanation has been provided for this answer.

235.

A battery of e.m.f 3.0V is connected across a potentiometer wire AB of length 10Ωm1 as illustrated in the diagram above. If the jockey J makes contact at the 30cm mark, determine the resistance of length AJ and voltage across AJ.

A.

3.0Ω; 0.9V

B.

3.0Ω; 3.0V

C.

3.3Ω; 0.3V

D.

3.3Ω; 9.0V

Correct answer is A

E = 3.0V; Rl=10Ωm1

l = 30cm = 0.3m; R = 10Ωm1×0.3m=3Ω

EV=l1l23V=10.3

= 3×0.31=0.9V