WAEC Physics Past Questions & Answers - Page 314

1,566.

Two parallel conductors carry equal currents in the same direction. Which of the following statement is not a correct observation?

A.

Each of teh conductors will experience a force

B.

Each of the conductors can move

C.

The forces on the conductors will be equal

D.

There are concentric lines of force around each conductor

E.

The two conductors will repel each other

Correct answer is E

No explanation has been provided for this answer.

1,567.

A cell can supply current of 0.8A and 0.4A through a 2Ω and a 3Ω resistors respectively. Calculate the internal resistance of the cell.

A.

0.2Ω

B.

0.4Ω

C.

1.0Ω

D.

3.0Ω

E.

9.0Ω

Correct answer is C

Assume the internal resistor = R

Current with 2 Ohm Resistor = 0.80A

Voltage = (R + 2) x 0.80 = V ; That is 0.8R + 1.6 = V ———————[[1]

Current with 3 Ohm Resistor = 0.40 A

Voltage = (R+3) x 0.40 = V ; That is 0.4R + 1.2 = V ————————[[2]

Subtracting 1 from 2 gives

--> (0.8 - 0.4) R 

     ( 1.6 - 1.2 ) 

     ( V - V ) 

Therefore 

0.4R  + 0.4 = 0

R = 0.4 /0.4 = 1 Ohms

1,568.

Local action is normally prevented from taking place in a simple electric cell by

A.

introducing an oxidising agent into the acid

B.

not drawing current continuously for long periods

C.

amalgamating the surface of the zinc plate

D.

using a porous pot to isolate the zinc plate from the acid

E.

using dilute sulphuric acid

Correct answer is C

No explanation has been provided for this answer.

1,570.

If the leaves a positively charged electroscope collapse completely as an object is brought near the cap of the electroscope, the objects possesses

A.

an equal amount of positive charge

B.

less amount of negative charge

C.

no charge

D.

a positive charge

E.

an equal amount of negative charge

Correct answer is E

No explanation has been provided for this answer.