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प्रश्न
Give Scientific reasons.
In the electric equipment producing heat e.g. iron, electric heater, boiler, toaster etc, an alloy such as Nichrome is used, not pure metals.
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उत्तर
In the electric equipment producing heat, such as iron, electric heater, boiler, toaster etc., an alloy such as Nichrome is used, not pure metals because of the following reasons:
- Resistivity of Nichrome is more compared to pure metal.
- Melting point of Nichrome is high as compared to pure metal.
- Nichrome does not get oxidised when heated in air whereas metal does.
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संबंधित प्रश्न
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?
What is nichrome? State its one use.
Give two reasons why nichrome alloy is used for making the heating elements of electrical appliances.
An electric kettle rated at 220 V, 2.2 kW, works for 3 hours. Find the energy consumed and the current drawn.
Why does the connecting cord of an electric heater not glow hot while the heating element does?
Write down the formula for the heat produced when a current I is passed through a resistor R for time t.
Explain why, the current that makes the heater element very hot, only slightly warms the connecting wires leading to the heater.
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
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.
Heat energy is being produced in a resistance in a circuit at the rate of 100 W. The current of 3 A is flowing in the circuit. What must be the value of the resistance?
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.
The ‘live’ and the ‘neutral’ wires have potential difference of _______.
What is used to turn off the sudden increase in current in the electrical circuit of the house nowadays?
Write two devices based on the heating effect of electric current.
Heating effect of current is called ______
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.
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?
What is Joule’s heating effect? How can it be demonstrated experimentally? List its four applications in daily life.
(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 component used as a safety device is electric circuit is ______.
Unscramble the following words:
SFEU
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.
An electric fuse has a body made of ceramic and two points for connecting the fuse wire.
What are the factors affecting heating effect of electric current?
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.
An electric fuse is a wire made up of a material having ______ melting point.
An electrochemical cell converts ______ energy into ______ energy.
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?
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.
State the law that explains the heating effect of current with respect to the measurable properties in an electrical circuit.
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 ______.
