351. A 100 watt electric bulb is used for 10 hours. What will be the cost of electricity consumed, if the consumption cost is Rs. 5 per unit?
1. Rs. 5
2. Rs. 10
3. Rs. 25
4. Rs. 50
Option “1” is correct. Energy Consumption of 100 watt electric bulb which is used for 10 hours = 100 × 10 = 1000 watt hour = 1 kilo watt hour = 1 unit. According to question the cost of 1 unit of electricity = Rs. 5
352. Which of the following metals is used as filament in lighting bulbs?
1. Iron
2. Molybdenum
3. Silver
4. Tungsten
Option “4” is correct. Tungsten metal is used as filament in lighting bulbs.
Option “2” is correct. The principle of atomic bomb is based on nuclear fission while fusion weapons are referred as thermonuclear bombs or hydrogen bomb.
354. The unit of power is-
1. Hertz
2. Volts
3. Watt
4. Neutrons
Option “3” is correct. In the field of Physics watt is measurement of power, describing the rate at which electricity is being used at a specific moment.
355. Optical fibre works on the principle of :
1. Total internal reflection
2. Refraction
3. Scattering
4. Interference
Option “1” is correct. The optical fibre is a very thin strand of glass or plastic cable for transmitting light from one point to another. They work on the principle of total internal reflection. There is no loss of signal through an optical fibre.
356. At what degree are the Centigrade and Fahrenheit temperatures the same?
1. 100°
2. 80°
3. –32°
4. –40°
Option “4” is correct. The temperature when both the Centigrade and Fahrenheit scales are same is -40 degrees.
357. When a ship floats on water
1. It displaces no water
2. The mass of water displaced is equal to the mass of the ship
3. The mass of water displaced is lesser than the mass of the ship
4. The mass of water displaced is greater than the mass of the ship
Option “2” is correct. According to Archimedes principle when a body is immersed fully or partially in a liquid, it experiences an upward force that is equal to the weight of the fluid displaced by it therefore the mass of water displaced is equal to the mass of the ship.
358. Which among the following determines the pitch of a sound?
1. Amplitude
2. Frequency
3. Loudness
4. Wavelength
Option “2” is correct. While frequency measures the cycle rate of the physical waveform, pitch is how high or low it sounds when you hear it. Pitch and Frequency are related to each other. A high pitch sound corresponds to a high frequency sound wave and a low pitch sound corresponds to a low frequency sound wave.
359. Which phenomena show the particle nature of light?
Option “3” is correct. The photoelectric effect is an phenomenon in which the emission of electrons occurs when a beam of light strikes a metal or a cathode surface. For emissions of electrons frequency of incident light is required to be greater than a minimum value called Threshold Frequency. Thus, show particle nature of light.
360. Electric Motor converts _____ energy to mechanical energy.
1. Sound
2. Mechanical
3. Chemical
4. Electrical
Option “4” is correct. An electric motor is an electrical machine that converts electrical energy into mechanical energy.
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