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प्रश्न
Which of the following substance contracts on heating?
पर्याय
Lukewarm water
Ice
Iron
Mercury
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उत्तर
Ice
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संबंधित प्रश्न
State four most common electrical appliances based on heating effect of electric current. Why do we use finely heated platinum wire in surgery?
Why does the cord of an electric heater not glow while the heating element does?
Name any two effects of electric current.
When current is switched ‘on’ in a room heater, it ______.
Why are the coils of electric irons and electric toasters made of an alloy rather than a pure metal?
How does the resistance of a wire vary with its:
diameter?
Explain why, the current that makes the heater element very hot, only slightly warms the connecting wires leading to the heater.
What is meant by the heating effect of current? Give two applications of the 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.
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.
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).
Name any six domestic appliances based on the heating effect of electric current.
Write the mathematical expression for Joule’s law of heating.
These days when current in the circuit suddenly increases _______ switches are used.
Which metal is used to make the filament of an electric bulb?
What is overloading?
What is used to turn off the sudden increase in current in the electrical circuit of the house nowadays?
Name any two appliances which works on the phenomenon of heating effect of electric current.
When does overloading occur?
Explain the application of heating effect of electric current in an electric bulb with a diagram.
Heating effect of current is called ______
An electric iron consumes energy at the rate of 420 W when heating is at the maximum rate and 180 W when heating is at the minimum rate. The applied voltage is 220 V. What is the current in each case?
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.
(a) Observe the diagram given below and state whether the bulb will glow or not when we switch on K.
(b) Is it safe to handle the bulb when the switch is OFF?
(c) Give a reason for your answer in (b).
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.
What are the uses of electromagnets?
Name the effect of the current responsible for the glow of the bulb in an electrical circuit.
An electrochemical cell converts ______ energy into ______ energy.
A fuse is used in an electric circuit to stop high currents flowing through the circuit.
The electric fuse works on the Joule heating principle.
Explain why fuse wire is always connected in a series arrangement.
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.
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?
