Electric Current is the flow of electric charge through a conductor. This topic covers current, voltage, resistance, Ohm's Law, electric circuits and electrical power. It is one of the most important topics in Physics for UPSC, SSC, Railway and other competitive examinations.
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?
Correct Answer:
(A) Rs. 5
Energy Consumption of 100-watt electric bulb which is used for 10 hours = 100 ×10
= 1000-watt hour
= 1 kilowatt hour
= 1 unit.
According to question the cost of 1 unit of electricity = Rs 5.
Correct Answer:
(A) There is no heat loss
When electrical energy is converted into motion, there is no heat loss.
Ques: 4
Electric motors operating at low voltages tend to burn out because –
Correct Answer:
(A) They draw more current which is inversely proportional to the voltage.
Electric motors operating at low voltages tend to burn out because they draw more current which is inversely proportional to the voltage.
Ques: 5
Faraday constant:
Correct Answer:
(D)
None of the above / More than one of the above.
The Faraday constant represents the magnitude of electric charge per mole of electrons. It is denoted by the symbol 'F' and is named after English scientist Michael Faraday. It is a universal constant. It has the currently accepted value F = 96485.332123 C.Mol–1.
Ques: 6
Nickel-Cadmium (Ni-Cd) battery is used in:
Correct Answer:
(D)
All of the above
The nickel-cadmium battery is a type of rechargeable battery using nickel oxide hydroxide and metallic cadmium as electrodes, while potassium hydroxide is used as alkaline electrolyte. It is used in calculator, cordless electronic appliances, transistors, portable power tools, photography equipment, flashlight etc.
Ques: 7
The temperature of the filament of lighted electric bulb is generally:
Correct Answer:
(C) 2000oC to 2500oC
Tungsten metal is used as filament in electric bulb. When electric current flows through it, its temperature goes up to 1500oC to 2500oC. Generally, electric bulbs convert only 5% to 10% of electric energy into light.