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प्रश्न
Which of the following substance contracts on heating?
विकल्प
Lukewarm water
Ice
Iron
Mercury
उत्तर
Ice
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संबंधित प्रश्न
Compute the heat generated while transferring 96000 coulomb of charge in one hour through a potential difference of 50 V.
When current is switched ‘on’ in a room heater, it ______.
The safety device based on the heating effect of electric current is called a ______.
Give two reasons why nichrome alloy is used for making the heating elements of electrical appliances.
Why are the coils of electric irons and electric toasters made of an alloy rather than a pure metal?
Why does the connecting cord of an electric heater not glow hot while the heating element does?
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?
A resistance of 25 Ω is connected to a 12 V battery. Calculate the heat energy in joules generated per minute.
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 elements of electrical heating devices are usually made of:
(a) tungsten
(b) bronze
(c) nichrome
(d) argon
How does the wire in the filament of a light bulb behave differently to the other wires in the circuit when the current flows?
What property of the filament wire accounts for this difference?
Identify the figure and give its use.
Identify the figure and give its use.
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).
Answer the following question.
Write the mathematical expression for Joule's law of heating.
These days when current in the circuit suddenly increases _______ switches are used.
Live wire and neutral wires have a 220 V potential difference.
Write scientific reason.
A coil made up of alloy Nichrome is used in the electric heater cooker as a resistor.
How can overloading be avoided?
Name some devices that run using heat effect of electric current
Explain the heating effect of electric current.
Mark the correct choice
- Assertion: Electric appliances with a metallic body have three wire connections.
- Reason: Three-pin connections reduce the heating of the connecting wires.
Why is parallel arrangement used in domestic wiring?
Three incandescent bulbs of 100 W each are connected in series in an electric circuit. In another circuit another set of three bulbs of the same wattage are connected in parallel to the same source.
- Will the bulb in the two circuits glow with the same brightness? Justify your answer.
- Now let one bulb in both the circuits get fused. Will the rest of the bulbs continue to glow in each circuit? Give reason.
Name two electric devices for each where
(i) the heating effect of current is used and
(ii) the magnetic effect of current is used.
Your teacher has shown you the following activity.
Activity: The teacher has wound a long insulated piece of wire around an iron nail in the form of a coil. The free ends of the wire are connected to a cell through a switch as shown in Figure 14.3. 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
Explain the working of an electric fuse.
It would cost a man Rs. 3.50 to buy 1.0 kW h of electrical energy from the Main Electricity Board. His generator has a maximum power of 2.0 kW. The generator produces energy at this maximum power for 3 hours. Calculate how much it would cost to buy the same amount of energy from the Main Electricity Board.
Assertion: A current-carrying wire should be charged.
Reason: The current in a wire is due to the flow of free electrons in a definite direction.
A fuse is used in an electric circuit to stop high currents flowing through the circuit.
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?
