Q282. Assertion (A): Transformer is useful for stepping up or stepping down voltages. Reason (R): Transformer is a device used in D.C. circuits. In the context of the above two statements, which one of the following is correct?

Assertion (A): In our houses, the current in the A.C. electricity line changes direction 60 times per second. Reason (R): The frequency of alternating voltage s

Assertion (A): Radio waves bend in a magnetic field. Reason (R): Radio waves are electromagnetic in nature.

Assertion (A): Radio waves bend in a magnetic field. Reason (R): Radio waves are electromagnetic in nature.

Assertion (A): The temperature of a metal wire rises when an electric current is passed through it. Reason (R): Collision of metal atoms with each other release

Assertion (A): With the increase of temperature, the viscosity of glycerine increases. Reason (R): Rise of temperature increases kinetic energy of molecules. Co

Assertion (A): The boiling point of water decreases as the altitude increases. Reason (R): The atmospheric pressure increases with altitude. Codes: (a) Both A a

Assertion (A): Unsaturated fats are more reactive compared with the saturated fats. Reason (R): Unsaturated fats have only single bonds in their structure.

Assertion (A): A jet aircraft moving at Mach Number equal to 1 travels faster at an altitude of 15 km than while moving at Mach Number equal to 1 near the sea l

Assertion (A): A jet aircraft moving at Mach Number equal to 1 travels faster at an altitude of 15 km than while moving at Mach Number equal to 1 near the sea l

Assertion (A): Small glass beads fixed on traffic signals glow brightly when light falls upon them. Reason (R): Light is totally reflected when the angle of inc

Assertion (A): The weight of a body decreases with the increase of altitude on earth. Reason (R): The earth is not a perfect sphere. Codes:

Assertion (A): An iron ball floats on mercury but gets immersed in water. Reason (R): The specific gravity of iron is more than that of mercury. Codes:

Assertion (A): Coal-based thermal power stations contribute to acid-rain. Reason (R): Oxides of carbon are emitted when coal burns.

Assertion (A): Dolly was the first cloned mammal. Reason (R): Dolly was produced by in vitro fertilization.

Assertion (A): A stick is dipped in water in a slanting position. If observed sideways, the stick appears short and bent at the surface of water. Reason (R): A

Assertion (A): Amoeba reproduces by fission. Reason (R): All unicellular organisms reproduce by asexual methods.

Assertion (A): Large cold storage plants use ammonia as refrigerant while domestic refrigerators use chlorofluoro- carbons. Reason (R): Ammonia can be liquefied

Which one of the following is printed on a commonly used fluorescent tube light?

What is the order of magnitude of electric resistance of the human body (dry)?

Two wires have their lengths, diameters and resistivities all in the ratio of 1: 2 If the resistance of the thinner wire is 10 ohm, the resistance of

Fluorescent tubes are fitted with a choke. The choke coil:

Consider the following statements: An ordinary light bulb has a rather short life because the: 1. filament wire is not uniform. 2. bulb cannot be evac

Consider the following statements regarding a motor car battery: 1. The voltage is usually 12 V. 2. Electrolyte used is hydrochloric acid. 3. Electrod

A fuse is used in mains electric supply as a safety device. Which one of the following statements about the fuse is correct?

Which one of the following is paramagnetic in nature?