Advertisements
Advertisements
Question
A resistance of 25 Ω is connected to a 12 V battery. Calculate the heat energy in joules generated per minute.
Advertisements
Solution
V =12 V
R = 25 Ω
t = 1 minute = 60
current, `I=V/R=12/25=0.48A`
Heat generated = I2Rt = (0.48)2(25)(60) = 345.6 J
APPEARS IN
RELATED QUESTIONS
Name any two effects of electric current.
When current is switched ‘on’ in a room heater, it ______.
What is nichrome? State its one use.
The heat produced by passing an electric current through a fixed resistor is proportional to the square of:
(a) magnitude of resistance of the resistor
(b) temperature of the resistor
(c) magnitude of current
(d) time for which current is passed
Which electric heating device in your home do you think have resistors which control the flow of electricity?
Give a scientific reason:
For electric power transmission, copper or aluminium wire is used.
Give Scientific reason.
In practice, the unit kWh is used for the measurement of electrical energy, rather than joule.
Identify the figure and give its use.
Give scientific reason :
In the electric equipment producing heat e.g. iron, electric heater, boiler, toaster, etc., an alloy such as Nichrome is used, not pure metals.
Find the odd one out and give its explanation.
Name any two appliances which works on the phenomenon of heating effect of electric current.
A fuse wire repeatedly gets burnt when used with a good heater. It is advised to use a fuse wire of:
An electric kettle consumes 1 kW of electric power when operated at 220 V. A fuse wire of what rating must be used for it?
B1, B2 and B3 are three identical bulbs connected as shown in Figure. When all the three bulbs glow, a current of 3A is recorded by the ammeter A.
- What happens to the glow of the other two bulbs when the bulb B1 gets fused?
- What happens to the reading of A1, A2, A3 and A when the bulb B2 gets fused?
- How much power is dissipated in the circuit when all the three bulbs glow together?
Match the following
| 1. | Bulb | a. | Conductor |
| 2. | Electroplating | b. |
Insulator |
| 3. | Pure water | c. | Heating effect of current |
| 4. | Salt solution | d. | Chemical effect of current |
A trip switch is a ______ safety device.
An electric kettle of 2 kW is used for 2h. Calculate the energy consumed in
- kilowatt hour and
- joules.
What is the heating effect of electric current?
Write an expression for the amount of heat produced in a resistor when an electric current is passed through it stating the meanings of the symbols used.
An electric iron is rated 220 V, 2 kW. If the iron is used for 3h daily find the cost of running it for one week if it costs ₹ 4.25 per kWh.
