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प्रश्न
These days when current in the circuit suddenly increases _______ switches are used.
विकल्प
MCA
MCC
MCD
MCB
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उत्तर
These days when current in the circuit suddenly increases MCB switches are used.
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संबंधित प्रश्न
Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
When current is switched ‘on’ in a room heater, it ______.
Write Joule's law of heating.
An electric heater is connected to the 230 V mains supply. A current of 8 A flows through the heater.
- How much charge flows around the circuit each second?
- How much energy is transferred to the heater each second?
An electric heater is connected to the 230 V mains supply. A current of 8 A flows through the heater.
(b) How much energy is transferred to the heater each second?
What is nichrome? State its one use.
Why are the coils of electric irons and electric toasters made of an alloy rather than a pure metal?
A heating coil has a resistance of 200 Ω. At what rate will heat be produced in it when a current of 2.5 A flows through it?
The electrical resistivities of four materials P, Q, R and S are given below:
| P | `6.84xx10^8`Ωm |
| Q | `1.70xx10^8`Ωm |
| R | ` 1.0xx10^15`Ωm |
| s | `11.0xx10^-7`Ωm |
Which material will you use for making: (a) heating element of electric iron (b) connecting wires of electric iron (c) covering of connecting wires? Give reason for your choice in each case.
Which electric heating device in your home do you think have resistors which control the flow of electricity?
Give a scientific reason.
Tungsten metal is used to make a solenoid type coil in an electric bulb.
Give a scientific reason:
For electric power transmission, copper or aluminium wire is used.
Solve the following example.
Two tungsten bulbs of wattage 100 W and 60 W power work on 220 V potential difference. If they are connected in parallel, how much current will flow in the main conductor?
Statement 1 : Electric current ( flow of electrons ) creates heat in the resistor.
Statement 2 : Heat in the resistor is created according to the rule of energy conservation.
Explain Statement 1 with the help of Statement 2.
Write the mathematical expression for Joule’s law of heating.
Compute the heat generated while transferring 96000 coulombs of charge in two hours through a potential difference of 40 V.
The electricity bill specifies the usage in _______.
Which of the following substance contracts on heating?
What is overloading?
Right or wrong sentence.
Live wire and neutral wires have a 220 V potential difference.
Name any two appliances which works on the phenomenon of heating effect of electric current.
What does overloading cause?
How can overloading be avoided?
True or False – If False give the correct answer
The fuse wire does not melts whenever there is overload in the wiring.
Name some devices that run using heat effect of electric current
An electric iron draws a current of 4 A when connected to 220 V mains. Its resistance must be:
A fuse wire repeatedly gets burnt when used with a good heater. It is advised to use a fuse wire of:
Which of the following gases are filled in electric bulbs?
Can we use the same fuse in a geyser and a television set? Explain.
Name two electric devices for each where
- heating effect of current is used and
- magnetic effect of current is used.
An electric fuse has a body made of ceramic and two points for connecting the fuse wire.
A trip switch is a ______ safety device.
Explain why fuse wire is always connected in a series arrangement.
Tara, after completing her exams, went to her grandmother's house along with her younger brother Rahul. One day, Rahul came home after playing and switched on the fan and air conditioner. At the same time, his grandmother was preparing a milkshake for him using a mixer. Suddenly, they heard a big sound and the electricity of the house got shut down. Tara is called an electrician. He said the main reason for supply to shut down was overloading.
- What is overloading?
- Is overloading and short the same? When does short-circuiting take place?
- How can the effects of overloading be avoided?
Find the odd one out.
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?
What is the heating effect of electric current?
Anannya responded to the question: Why do electrical appliances with metallic bodies are connected to the mains through a three-pin plug, whereas an electric bulb can be connected with a two-pin plug?
She wrote: Three-pin connections reduce heating of connecting wires.
- Is her answer correct or incorrect? Justify.
- What is the function of a fuse in a domestic circuit?
When a current I flows through a wire of resistance R for time t then the electrical energy produced is given by ______.
