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महाराष्ट्र राज्य शिक्षण मंडळएस.एस.सी (इंग्रजी माध्यम) इयत्ता १० वी

Give scientific reason : In the electric equipment producing heat e.g. iron, electric heater, boiler, toaster etc., an alloy such as Nichrome is used, not pure metals. - Science and Technology 1

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प्रश्न

Give scientific reason :
In the electric equipment producing heat e.g. iron, electric heater, boiler, toaster, etc., an alloy such as Nichrome is used, not pure metals.

एका वाक्यात उत्तर

उत्तर

Resistivity of alloys like nichrome is more than pure metals so they will get heated easily on the passage of a small amount of current. They also have a high melting point and do not oxidize readily at high temperature. So 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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2018-2019 (March) Set 1

संबंधित प्रश्‍न

An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.


Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?


Write Joule's law of heating.


What is nichrome? State its one use.


Why is a series arrangement not used for connecting domestic electrical appliances in a circuit?


Write down the formula for the heat produced when a current I is passed through a resistor R for time t.


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


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
(bx × z × y2
(cy × z2 × x
(dy × z × 


Which of the following characteristic is not suitable for a fuse wire?

(a) thin and short
(b) thick and short
(c) low melting point
(d) higher resistance than rest of wiring


Two exactly similar heating resistances are connected (i) in series, and (ii) in parallel, in two different circuits, one by one. If the same current is passed through both the combinations, is more heat obtained per minute when they are connected in series or when they are connected in parallel? Give reason for your answer.


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).


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.


Name the factors on which the heat produced in a wire depends when current is passed in it, and state how does it depend on the factors stated by you.


Rewrite the following statement by selecting the correct option:

1 A = ____________ mA.


Answer the following question.
Write the mathematical expression for Joule's law of heating.


Find the odd one out and give its explanation.


Live wire and neutral wires have a 220 V potential difference.


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 ______


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


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?


An electric iron draws a current of 4 A when connected to 220 V mains. Its resistance must be:


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.


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.

  1. Will the bulb in the two circuits glow with the same brightness? Justify your answer.
  2. Now let one bulb in both the circuits get fused. Will the rest of the bulbs continue to glow in each circuit? Give reason.

Can we use the same fuse in a geyser and a television set? Explain.


Name two electric devices for each where

(i) the heating effect of current is used and

(ii) the magnetic effect of current is used.


An MCB can be used instead of a fuse in an electrical circuit.


What is an electric fuse made up of?


A student boils water in an electric kettle for 20 minutes. Using the same mains supply he wants to reduce the boiling time of water. To do so should he increase or decrease the length of the heating element? Justify your answer.


Explain why fuse wire is always connected in a series arrangement.


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?

In which of the following applications of Iron, rusting will occur most? Support your answer with valid reason.

A B C D

In a set up the students coated iron nails with zinc metal and noted that, iron nails coated with zinc prevents rusting. They also observed that zinc initially acts as a physical barrier, but an extra advantage of using zinc is that it continues to prevent rusting even if the layer of zinc is damaged. Name this process of rust prevention and give any two other methods to prevent rusting.


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