JAMB Physics Past Questions & Answers - Page 170

847.

In the circuit above R is a resistor whose resistance increases with increase in temperature. L1 and L2 are identical lamps. If the temperature of R increases,

A.

L1 becomes brighter and L2 becomes dimmer

B.

L1 becomes brighter and L2 does not change

C.

L2 becomes dimmer and L1 does not change

D.

L1 becomes dimmer and L2 does not change

E.

L1 and L2 becomes brighter

Correct answer is A

No explanation has been provided for this answer.

848.

A 90W immersion heater is used to supply energy for 5 minutes. The energy supplied is used to completely melt 160g of a solid at its melting point. Calculate the specific latent heat of the solid.

A.

2.81jg-1

B.

6.25Jg-1

C.

8.89Jg-1

D.

168.75Jg-1

E.

5333.33Jg-1

Correct answer is D

pt = ml 80

90 x 5 x 60 = 160 x L

L = \(\frac{27000}{160}\)

= 168.75Jg-1

= 168.75

849.

Using the data in the circuit illustrated above, calculate the value of R

A.

0.02\(\Omega\)

B.

0.05\(\Omega\)

C.

5.00\(\Omega\)

D.

20.00\(\Omega\)

E.

50.00\(\Omega\)

Correct answer is E

R = \(\frac{V}{T} = \frac{2v}{40 \times 10^{-3}}\)

= 50.00\(\Omega\)

850.

Which of the following is stored by dry Leclanche cell?

A.

chemical energy

B.

nuclear energy

C.

solar energy

D.

heat energy

E.

electrical energy

Correct answer is A

The energy stored in the dry Leclanche cell is the chemical energy. It converts the chemical energy to electrical energy.