JAMB Physics Past Questions & Answers - Page 344

1,716.

Calculate the energy of the third level of an atom if the ground state energy is - 24.8eV

A.

-9.20eV

B.

-8.20eV

C.

-2.75eV

D.

-1.75eV

Correct answer is C

\(E_3 = \frac{E}{n^2}\)

\(E_3 = \frac{-24.8}{3^2}\)

\(E_3 = 2.75eV\)

1,717.

If a current of 2.5A flows through an electrolyte for 3 hours and 1.8g of a substance is deposited, what is the mass of the substance that will be deposited if a current of 4A flows through it for 4.8 hours?

A.

2.4g

B.

3.2g

C.

4.6g

D.

4.8g

Correct answer is C

First let's find z

z = \(\frac{M}{It}\)

z = \(\frac{1.8}{2.5 \times (3 \times 60 \times 60)}\)

Therefore, the new M equals

M = zIt

M = \(\frac{1.8 \times 4 \times 4.8 \times 60 \times 60}{2.5 \times 3 \times 60 \times 60}\)

M = 4.6g

1,718.

Induced emfs are best explained using

A.

Ohm's law

B.

Faraday's law

C.

Colomb's law

D.

Lenz's law

Correct answer is B

No explanation has been provided for this answer.

1,719.

To convert a galvanometer to a voltmeter, a

A.

high resistance is connected to it in series

B.

high resistance is connected to it in parallel

C.

low resistance is connected to it in parallel

D.

low resistance is connected to it in series

Correct answer is A

No explanation has been provided for this answer.

1,720.

When a charge moves through an electric circuit in the direction of an electric force, it

A.

gains both potential and kinetic energy

B.

gains potential energy and lose kinetic energy

C.

loses potential energy and gains kinetic energy

D.

loses both potential and kinetic energy

Correct answer is C

No explanation has been provided for this answer.