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प्रश्न
State four most common electrical appliances based on heating effect of electric current. Why do we use finely heated platinum wire in surgery?
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उत्तर
The four most common appliances based on the heating effect of electrical current are electric iron, electric heater, electric oven and electric toaster. Finely heated platinum wire is used in surgery for cutting tissues much more efficiently than a knife.
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संबंधित प्रश्न
Why is the tungsten used almost exclusively for filament of electric lamps?
How does the resistance of a wire vary with its area of cross-section?
Give two reasons why nichrome alloy is used for making the heating elements of electrical appliances.
How does the resistance of a wire vary with its:
diameter?
The current passing through a room heater has been halved. What will happen to the heat produced by it?
What is meant by the heating effect of current?
The current passing through an electric kettle has been doubled. The heat produced will become:
(a) half
(b) double
(c) four time
(d) one-fourth
An electric fuse works on the:
(a) chemical effect of current
(b) magnetic effect of current
(c) lighting effect of current
(d) heating effect of current
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
(b) x × z × y2
(c) y × z2 × x
(d) y × z × x
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.
Give a scientific reason:
For electric power transmission, copper or aluminium wire is used.
Identify the figure and give its use.
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?
An electric iron of 1100 W is operated for 2 hrs daily. What will be the electrical consumption expenses for that in the month of April? (The electric company charges Rs 5 per unit of energy).
Write the mathematical expression for Joule’s law of heating.
What is the heating effect of electric current?
What is used to turn off the sudden increase in current in the electrical circuit of the house nowadays?
When does overloading occur?
What does overloading cause?
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 current of 1 A is drawn by a filament of an electric bulb. Number of electrons passing through a cross-section of the filament in 16 seconds would be roughly:
Assertion: Bending of wire decreases the resistance of the electric wire.
Reason: The resistance of a conductor depends on length, thickness, nature of material and temperature of the conductor.
How does use of a fuse wire protect electrical appliances?
What is Joule’s heating effect? How can it be demonstrated experimentally? List its four applications in daily life.
An electric component used as a safety device is electric circuit is ______.
An electric cell produces electricity from the ______ ______ in it.
Name two electric devices for each where
- heating effect of current is used and
- magnetic effect of current is used.
Paheli took a wire of length 10 cm. Boojho took a wire of 5 cm of the same material and thickness. Both of them connected the wires as shown in the circuit given in the following figure. The current flowing in both the circuits is the same.
- Will the heat produced in both cases be equal? Explain.
- Will the heat produced be the same if the wires taken by them are of equal lengths but of different thickness? Explain.
Explain the working of an electric fuse.
What is a trip switch?
The electric fuse works on the Joule heating principle.
In the electric equipment producing heat like iron, electric heater, boiler, toaster etc., an alloy such as nichrome is used, not pure metals.
In which of the following applications of Iron, rusting will occur most? Support your answer with valid reason.
| A | B | C | D |
 |
 |
 |
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The graph of voltage vs current for four different materials is shown below.
Which of these four materials would be used for making filament of bulb?
