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JAMB Physics Past Questions & Answers - Page 110

546.

Two 2.0Ω resistors can be combined circuit to give an overall resistance of

A.

0.5Ω only

B.

1.0 Ω only

C.

either 0,5Ω or 1.0 Ω

D.

either 1.0Ω or 4.0 Ω

E.

either 0.5Ω, 1.0Ω or 4.0Ω

Correct answer is D

No explanation has been provided for this answer.

547.

Calculate the peak voltage of a mains supply of r.ms. value 220V.

A.

121 V

B.

156 V

C.

225 V

D.

240 V

E.

311 V

Correct answer is E

No explanation has been provided for this answer.

548.

If the first position of resonance in a resonance tube is 18.0cm from the open end, the distance from the open end to the next position of resonance will be

A.

24.0cm

B.

27.0cm

C.

36.0cm

D.

45.0cm

E.

54.0cm

Correct answer is E

No explanation has been provided for this answer.

549.

The image formed by a converging lens of focal length is of a distance of 2f from the lens. Calculate the lateral magnification produced

A.

0.5

B.

1

C.

1.5

D.

2

E.

3

Correct answer is B

Using the lens formula,

1v+1u=1f

Where u, v and f are the object distance, image distance and focal length respectively.

\frac{1}{u} = \frac{1}{2f} - \frac{1}{f} \implies \frac{1}{u} = \frac{1}{2f}

u = 2f

\therefore Magnification = \frac{\text{image distance}}{\text{object distance}}

= \frac{2f}{2f}

= 1

550.

An electric iron rated 250 V has a coil of resistance 125Ω. What is the cost of using it for I hour at 10k per kWh?

A.

1.25k

B.

2.50k

C.

5.00k

D.

10.00k

E.

20.00k

Correct answer is C

No explanation has been provided for this answer.