JAMB Physics Past Questions & Answers - Page 196

976.

Natural radioactivity consists of the emission of

A.

\( \alpha \) -particle and \( \beta \) rays

B.

\( \alpha \) -particle and X-rays

C.

\( \gamma \)-rays and X-rays

D.

\( \alpha \)-particle, \( \beta \) rays and \( \gamma \)-rays

E.

\( \alpha \) -particle, \( \beta \) rays, \( \gamma \)-rays and X-rays

Correct answer is D

No explanation has been provided for this answer.

977.

The activity of a radioactive substance depends on

A.

temperature and purity

B.

temperature and age

C.

purity and age

D.

age, purity and temperature

E.

none of the above

Correct answer is E

No explanation has been provided for this answer.

978.

In the process of electrification by induction, the amount of induced charge in relation to the inducing charge is the

A.

same in sign and quantity

B.

same in sign but greater

C.

opposite in sign but greater

D.

opposite in sign but less

E.

opposite in sign but equal

Correct answer is E

No explanation has been provided for this answer.

979.

According to Ohm's law, the ratio V/I is constant for

A.

an electrolyte

B.

a diode

C.

a transistor

D.

silver

E.

all of the above

Correct answer is D

No explanation has been provided for this answer.

980.

A cell has an open circuit voltage V1 and a closed circuit voltage V2 when a current is flowing through it. Therefore, the internal resistance of the cell is

A.

\(\frac{V_2}{I}\)

B.

\(\frac{V_1}{I}\)

C.

\(\frac{(V_1 + V_2)}{I}\)

D.

\(\frac{(V_1 - V_2)}{I}\)

E.

\(\frac{(V_2 - V_1)}{I}\)

Correct answer is E

On open circuit, V1 = I; On closed circuit V2 = IR + Ir

V2 = V1 + Ir

r = \(\frac{(V_2 - V_1)}{I}\)