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Why Does the Connecting Cord of an Electric Heater Not Glow Hot While the Heating Element Does? - Science

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प्रश्न

Why does the connecting cord of an electric heater not glow hot while the heating element does?

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उत्तर

It is so because the connecting cord has a very low resistance. So, it does not get enough heat to glow.

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पाठ 1: Electricity - Exercise 8

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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 ______.


An electric heater is connected to the 230 V mains supply. A current of 8 A flows through the heater. 

(a) How much charge flows around the circuit each second?


Name the material which is used for making the filaments of an electric bulb.


The heat produced in a wire of resistance 'x' when a current 'y' flows through it in time 'z' is given by:

(a) x2 × y × z
(bx × z × y2
(cy × z2 × x
(dy × z × 


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.

 


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? 


Name any six domestic appliances based on the heating effect of electric current.


The electricity bill specifies the usage in _______.


Name some devices that run using heat effect of electric current


Name any two appliances which work under the principle of heating effect of current.


Mark the correct choice

  1. Assertion: Electric appliances with a metallic body have three wire connections.
  2. Reason: Three-pin connections reduce the heating of the connecting wires.

An electric cell produces electricity from the ______ ______ in it.


Your teacher has shown you the following activity.


Activity: Teacher has wound a long insulated piece of wire around an iron nail in the form of a coil. Free ends of the wire are connected to a cell through a switch as shown in the following figure. The current is switched on and some pins are placed near the ends of the nail.

Write down any three questions that come to your mind about this activity.


Name a few appliances which work on the basis of the heating effect of current.


An electric fuse is a wire made up of a material having ______ melting point.


A trip switch is a ______ safety device.


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.

  1. What is overloading?
  2. Is overloading and short the same? When does short-circuiting take place?
  3. How can the effects of overloading be avoided?

Find the odd one out.


1 kWh is equal to ______.


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