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Physics problems: electricity

electric power (heat)

 

 

Problem 42.

The current passing through a room heater has been halved. What will happen to the heat produced by it?

Solution

 

Problem 43.

An electric iron of resistance 20 ohm draws a current of 5 amperes. Calculate the heat produced in 30 seconds.

Solution

 

Problem 44.

A resistance of 40 ohms and one of 60 ohms are arranged in series across 220 volt supply. Find the heat in joules produced by this combination in half a minute.

Solution

 

Problem 45.

A resistance of 25 ohm is connected to a 12 V battery. Calculate the heat energy in joules generated per minute.

Solution

 

Problem 46.

100 joules of heat is produced per second in a 4 ohm resistor. What is the potential difference across the resistor? 

Solution

 

 

 

Problem 47.

An electric iron is connected to the mains power supply of 220 V. When the electric iron is adjusted at minimum heating’ it consumes a power of 360 W but at ‘maximum heating’ it takes a power of 840 W. Calculate the current and resistance in each case.

Solution

 

Problem 49.

Which has a greater resistance, a 100 watt bulb or a 60 watt bulb?

Solution

 

Problem 50.

An electric bulb is rated at 220 V, 100 W. What is its resistance?

Solution

 

Problem 51.

An electric bulb is connected to a 220 V power supply line. If the bulb draws a current of 0.5 A, calculate the power of the bulb.

Solution

 

 

 

Problem 52.

In which of the following cases more electrical energy is consumed per hour?

Case 1. A current of 1 ampere passed through a resistance of 300 ohms

Case 2. A current of 2 amperes passed through a resistance of 100 ohms. 

Solution

 

Problem 53.

In a house two 60 W electric bulbs are lighted for 4 hours, and three 100 W bulbs for 5 hours every day. Calculate the electric energy consumed in 30 days.

Solution

 

Problem 54.

If the potential difference between the ends of a wire of fixed resistance is doubled, by how much does the electric power increase?

Solution

 

Problem 55.

Which uses more energy: a 250 W TV set in 1 hour or a 1200 W Toaster in 10 minutes?

Solution

 

 

 

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