JAMB Physics Past Questions & Answers - Page 94

467.

A wire of cross-sectional area 0.60mm2 has a restivity of 7.2 x 10-7 \(\Omega\). Calculate the length of wire that will have a resistance of 3\(\Omega\).

A.

0.25m

B.

2.50m

C.

3.60m

D.

36.00

Correct answer is B

R = \(\frac{PL}{A}\)

C = \(\frac{RA}{P}\)

C = \(\frac{0.60 \times 10^{-6} \times 3}{7.2 \times 10^{-7}}\)

C = 2.50m

468.

The symbol illustrated above is that of a resistor?

A.

which absorb light

B.

which emits light

C.

which absorbs heat to function properly

D.

whose resistance is light dependent

Correct answer is D

A photoresistor or light dependent resistor is an electronic component that is sensitive to light. When light falls upon it, then the resistance changes.

Used where there is a need to sense the presence and absence of light is necessary. These resistors are used as light sensors and the applications of LDR mainly include alarm clocks, street lights, light intensity meters, burglar alarm circuits.

470.

Which of the following statements is correct? When capacitors of different values are connected in series

A.

the same charge flows through them

B.

the same voltage appears across each capacitor

C.

different quantities of charges flow through them in different voltages across them

D.

different quantities of charges flows through them with the same voltage across them

Correct answer is A

No explanation has been provided for this answer.