JAMB Physics Past Questions & Answers - Page 250

1,246.

When a transformer has more secondary windings than primary windings, it?

A.

has a smaller secondary current

B.

has a greater power output

C.

is a step-down transformer

D.

increases the total energy output

Correct answer is A

A transformer that increases the voltage from primary to secondary (more secondary winding turns than primary winding turns) is called a step-up transformer.

1,247.

Two capacitance of 6\(\mu\)F and 8\(\mu\)F are connected in series. What additional capacitance must be connected in series with this combination to give a total of 3\(\mu\)F

A.

3\(\mu\)F

B.

16\(\mu\)F

C.

24\(\mu\)F

D.

30\(\mu\)F

Correct answer is C

3 = \(\frac{6 \times 8 \times c}{(6 \times 8) + (6 \times c) + (8 \times c}\)

therefore, C = 24\(\mu\)F

1,248.

If the angle of declination in a place is 10°E, calculate the true geographic bearing if the compass reads N40°E

A.

N50oE

B.

N40oE

C.

N30oE

D.

N25oE

Correct answer is A

The true declination is calculated by adding the reading of compass bearing to the declination at that place.

= N40°E + 10° = N50°E

1,249.

Four lenses are being considered for use as a microscope objective. Which of the following focal lengths is most suitable?

A.

-5mm

B.

+5mm

C.

-5cm

D.

+5cm

Correct answer is B

No explanation has been provided for this answer.