# Physics Past Questions | JAMB, WAEC, NECO and Post UTME Past Questions

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### Question 4751

The efficiency of energy conversion on the energy flow through a hydroelectric power is?

### Options

A) $$\frac{E1}{E2}$$

B) $$\frac{E3}{E2}$$

C) $$\frac{E2}{E1}$$+ E2

D) $$\frac{E2}{E3}$$ + E1

### Question 4752

An object weighs 30N in air and 21N in water. The weight of the object when completely immersed in a liquid of relative density 1.4 is

A) 25.2N

B) 17.4N

C) 12.6N

D) 9.0N

### Question 4753

Which of the following instruments is most suitable for measuring the outside diameter of a narrow pipe in a few millimeters in diameter?

### Options

A) Pair of calipers

B) Meter rule

C) Micrometer screw gauge

D) Tape rule

### Question 4754

Electrical power is transmitted at a high voltage rather than a low voltage because the amount of energy loss is due to

### Options

A) Heat dissipation

B) Production of eddy currents

C) Excessive current discharge

D) Excessive voltage discharge

### Question 4755

If the focal length of a camera is 20cm, the distance from the film at which the lens must be set to produce a sharp image of 100cm away is

A) 17cm

B) 20cm

C) 25cm

D) 100cm

### Question 4756

A lens of focal length 15cm forms on erect image which is three times the size of the object. The distance between the object and the image is ___.

A) 10cm

B) 20cm

C) 30cm

D) 40cm

### Question 4757

The photo cell works on the principle of the

### Options

A) Voltaic cell

B) Emission of electron by incident radiation

C) Emission of protons by incident radiation

D) Photographic plate

### Question 4758

When a known standard resistor of 2.0 is connected to the 0.0cm end of a metre bridge, the balance point is found to be at 55.0cm

A) 1.10Ω

B) 1.64Ω

C) 2.44Ω

D) 27.50Ω

### Question 4759

A resistor connected to a 12V battery draws a current of 2A. The energy dispatched in the resistor in 5 minutes is ___.

A) 3,600J

B) 6,000J

C) 7,200J

D) 14,400J

### Question 4760

A solid weighs 45N and 15N respectively in air and water. Determine the relative density of the solid

A) 0.33

B) 0.50

C) 1.50

D) 3.00