Railway Science (Physics-Work, Energy and Power)

Total Questions: 50

1. Identify the INCORRECT relation between power (P). Current(I), Resistance (R) and potential difference (V). [RRC Group D 23/08/2022 (Afternoon)]

Correct Answer: (a) P = IR²
Solution:

The rate of transfer of electrical energy is termed electric power.The electric power is measured in watts (W) which is its SI unit, and electric power is represented by P. Where P = 𝑉²/R = I²R. Two types of electrical power :
DC power - Product of voltage and current and is produced by DC sources like generators, batteries, fuel cells, etc. AC power - A flow of charge that exhibits a periodic change in direction.

2. Conversion of energy in electric motor is: [RRC Group D 14/09/2022 (Afternoon)]

Correct Answer: (d) Electrical energy to mechanical energy
Solution:

Electric Generators convert Kinetic energy / Mechanical Energy to Electric Energy. Microphone converts Sound Energy to Electric Energy. Thermocouple converts Heat Energy to Electrical Energy. Electric lamp converts Electrical Energy to Heat Energy and Light Energy.

3. In an electrical geyser ______ energy is converted to _______. [RRC Group D 14/09/2022 (Evening)]

Correct Answer: (a) Electrical, heat
Solution:

Electric geyser works on the principle of joule heating. Electric Generators convert Kinetic energy / Mechanical Energy to Electric Energy. Microphone converts Sound Energy to Electric Energy. Thermocouple converts Heat Energy to Electrical Energy. Electric lamp converts Electrical Energy to Heat Energy and Light Energy.

4. The common domestic power supplied in India is given by which of the following? [RRC Group D 17/09/2022 (Evening)]

Correct Answer: (b) 220V, 50Hz
Solution:

The government of India chooses the home power supply based on the environment. The main voltage (220V), and the frequency is 50 Hz. We utilize highresistance lines to distribute this voltage, hence the power will be quite large because power is calculated as the square of voltage times resistance. The United States (110V, 60Hz) - used, as this is considered a safe voltage level for DC systems. All electrical goods created for the Indian market are set up to operate best at 50Hz.

5. The energy lost in the form of heat in an electrical circuit is, [RRC Group D 26/09/2022 (Morning)]

Correct Answer: (a) directly proportional to the resistance
Solution:

When energy is transformed from one form to another, or moved from one place to another there is energy loss. Heat is the transfer of kinetic energy from a source of energy to a medium and is proportional to resistance for the same current. From this formula, the Heat is directly proportional to Resistance. H = 𝐼²𝑅𝑇.Here I = current, R = resistance and T = time. H = Heat.

6. The power input to the circuit when charge of Q coulomb is flowing for t seconds for a potential difference of V volt is _______. [RRC Group D 26/09/2022 (Afternoon)]

Correct Answer: (c) P = 𝑉𝑄/t
Solution:

7. Resistance is represented by _________ . [RRC Group D 27/09/2022 (Afternoon)]

Correct Answer: (a) work done /(charge × current)
Solution:Resistance is the opposition that a substance offers to the flow of electric
current, Unit: Ohm. Current is a flow of electrical charge carriers, usually
electrons or electron-deficient atoms, Unit: Ampere. Charge is the physical
property of matter that causes it to experience a force when placed in an
electromagnetic field, Unit: Coulomb.

8. The rate at which electrical energy is dissipated in an electric circuit is called ________ . [RRC Group D 30/09/2022 (Afternoon)]

Correct Answer: (b) electric power
Solution:

Any rate of work done is called power. Rate of electric work done is called electric power. Electric power is the rate at which electric energy is dissipated or consumed in an electric circuit, given by: P = VI = I²R = 𝑉²/R.

9. The telephone was invented in: [RRB NTPC CBT - I (01/02/2021) Evening]

Correct Answer: (b) 1876
Solution:

Alexander Graham Bell successfully received a patent for the telephone and secured the rights to the discovery. Elisha Gray is best known for his development of a telephone prototype in 1876 in Highland Park, Illinois. Some Inventions and Inventors: Television (John Baird), Gramophone and Bulb (Thomas Edison), Mobile Phone (Martin Cooper), Radio (Guglielmo Marconi), Airplane (Wright Brothers).

10. Which energy of the wind does a windmill use? [RRB NTPC CBT - I (09/02/2021) Evening]

Correct Answer: (b) Kinetic energy
Solution:

Wind turbines are the windmill's modern equivalent, converting the kinetic energy in wind into clean, renewable electricity. Tamil Nadu is a leader in Wind Power in India with favorable wind conditions along its coastline. Muppandal wind farm (Kanyakumari) : The largest wind power plant in India, Total capacity - 1500 MW, . The Gansu Wind Farm in China - The largest wind farm in the world, with a target capacity of 20,000 MW .