# General Science Quiz – Physics – 1 – RRB Group D 2018

Hello and welcome to exampundit. Here is a set of General Science Quiz on Physics for RRB Group D 2018 Examination.

1. An iron needle sinks in water whereas a ship made of iron floats on it because

(a) the edge of the needle is pointed

(b) the ship is flat

(c) the ship is driven by powerful engine

(d) specific gravity of the needle is greater than that of water displaced by it.

Option: D

Explanation:

Because the specific gravity of the needle is greater than that of water displaced by it.
Specific gravity (or relative density)
= Density of the substance/Density of water at 4°C
The average density of iron needle is greater than water, therefore, it sinks.

1. The cloudy nights are warmer than clear nights because

(a) clouds prevent escape of radiation of heat from the ground and the air.

(b) absorb sunlight in the day and radiate the same in night.

(c) clouds make the atmosphere damp and generate heat.

(d) clouds obstruct the movement of air which creates heat.

Option: A

Explanation:

The cloudy nights are warmer because clouds prevent escape of radiation of heat from the ground and the air

1. Food gets cooked faster in a pressure cooker because

(a) water starts boiling at a lower temperature due to high pressure

(b) water starts boiling at a higher temperature due to high pressure

(c) water boils only at 100°C but the heat content is higher at high pressure

(d) convection currents are set inside the cooker

Option: A

Explanation:

Because water starts boiling at a lower temperature due to high pressure. According to Gay-Lussac’s law r ∝ T.

1. It is more comfortable to wear white cloths in summer because

(a) they reflect heat falling on them.

(b) they radiate heat tansferred from the body.

(c) they absorb perspiration.

(d) they are soothing to the eye.

Option: A

Explanation:

The white clothes reflect heat falling on them in summer and they absorb the least from the sun.

1. Of the two bulbs in a house, one glows brighter than the other. Which of the following statements is correct?

(a) The brightness does not depend on resistance.

(b) Both the bulbs have the same resistance.

(c) The brighter bulb has larger resistance.

(d) The dimmer bulb has larger resistance.

Option: D

Explanation: The dimmer bulb has larger resistance than the brighter one.
Power of the bulb ∝ 1 / Resistance
Resistance is the obstruction offer to the flow of current.

1. A fluorescent tube is preferred to an electric bulb because

(a) it has a larger light emitting surface.

(b) voltage fluctuations do not affect it.

(c) in a tube electrical energy is almost converted into light.

(d) None of these

Option: C

Explanation:

In a fluorescent tube, electrical energy is almost converted into light. The inner wall of the fluorescent tube is coated with phosphorus which immediately transformed into bright light.

1. Consider the following statements in respect of a jet engine and a rocket:

(I) A jet engine uses the surrounding air for its oxygen supply and so is unsuitable for motion in space.

(II) A rocket carries its own supply of oxygen in the gas form as a fuel.

Which of the above statement(s) is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Option: C

Explanation:

In respect of a jet engine and a rocket, both the given statements are correct.

1. The leaning tower of Pisa does not fall because

(a) it is tappered at the top.

(b) it covers a large base area.

(c) its centre of gravity remains at the lowest position.

(d) the vertical line through the centre of gravity of the tower falls within the base.

Option: D

Explanation:

Because the vertical line through the centre of gravity of the tower falls within the base.

1. Given below are two statements:

Assertion (A): Universe is expanding.

Reason (R): The result is based on red shift of spectra of galaxies.

Codes:

(a) Both A and R are true and R is the correct explanation of A.

(b) Both A and R are true, but R is not the correct explanation of A.

(c) A is true, but R is false.

(d) A is false, but R is true.

Option: A

1. Electronic motors operating at low voltages tend to burn out because

(a) they draw more current which is inversely proportional to the voltage.

(b) they draw more current which is inversely proportional to the square root of the voltage.

(c) they draw heat proportional to V2.

(d) low voltage sets in electrical discharge.

Option: A

Explanation: Electronic motors draw more current which is inversely proportional to the voltage, therefore, more heat
H = I²Rt is generated

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