NECO Physics Past Questions & Answers - Page 34

166.

Lenz’s law of electromagnetic induction states that

A.

a force is exerted on a current carrying conductor in a magnetic field

B.

the induced current in a conductor is in such a direction as to oppose the change producing it

C.

the magnitude of the induced electromotive force in a circuit is proportional to the rate of change of the number of lines of force linking the circuit

D.

the magnitude of the induced electromotive force is proportional to the current producing the magnetic flux

E.

whenever there is a change in the magnetic flux linked with the circuit, an electromotive is induced

Correct answer is B

No explanation has been provided for this answer.

167.

Which of the following statement(s) is/are correct about the isotopes of an elements? They have the same

I. chemical properties
II. nucleon number
III proton number

A.

I only

B.

II only

C.

I and II only

D.

I and III only

E.

I,II and III

Correct answer is D

No explanation has been provided for this answer.

169.

A ball of mass m moving at velocity u collides with another ball of equal mass at rest. If the two balls move off together after the impact, calculate their common velocity.

A.

\(\frac{u}{v}\)

B.

\(\frac{mu}{2}\)

C.

u

D.

2u

E.

\(\frac{u}{m}\)

Correct answer is A

No explanation has been provided for this answer.

170.

A body is launched from the earth’s surface, of radius R, so that it just escapes from the gravitational influence of the earth; If the gravitational constant is G and the mass of the earth is M, what is the escape velocity of the boby.

A.

\(\sqrt{2GM}\) รท R

B.

\(\frac{\sqrt{2GM}}{R}\)

C.

\(\frac{\sqrt{2G}}{MR}\)

D.

\(\sqrt{2GMR}\)

E.

\(\frac{\sqrt{R}}{2GM}\)

Correct answer is B

No explanation has been provided for this answer.