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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.

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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
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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

State four most common electrical appliances based on heating effect of electric current. Why do we use finely heated platinum wire in surgery?


An electric iron of resistance 20 Ω takes a current of 5 A. Calculate the heat developed in 30 s.


When current is switched ‘on’ in a room heater, it ______.


The safety device based on the heating effect of electric current is called a ______.


An electric heater is connected to the 230 V mains supply. A current of 8 A flows through the heater. 

(b) How much energy is transferred to the heater each second?


Why does the connecting cord of an electric heater not glow hot while the heating element does?


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.


 How much heat will an instrument of 12 W produce in one minute if it is connected to the heat produced by it?  


What is meant by the heating effect of current? Give two applications of the heating effect of current. 


The heat produced by passing an electric current through a fixed resistor is proportional to the square of:  

(a) magnitude of resistance of the resistor
(b) temperature of the resistor
(c) magnitude of current
(d) time for which current is passed


The elements of electrical heating devices are usually made of:

(a) tungsten
(b) bronze
(c) nichrome
(d) argon


If the current flowing through a fixed resistor is halved, the heat produced in it will become:


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.


Three heaters each rated 250 W, 100 V are connected in parallel to a 100 V supply. Calculate:

  1. the total current taken from the supply
  2. the resistance of each heater and
  3. the energy supplied in kWh to the three heaters in 5 hours.

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.


Give a scientific reason:

For electric power transmission, copper or aluminium wire is used.


Give Scientific reason.

In practice, the unit kWh is used for the measurement of electrical energy, rather than joule.


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.


Why does tungsten metal used to make solenoid type coil in an electric bulb?


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.


Name any six domestic appliances based on the heating effect of electric current.


Compute the heat generated while transferring 96000 coulombs of charge in two hours through a potential difference of 40 V.


These days when current in the circuit suddenly increases _______ switches are used.


Name any two appliances which works on the phenomenon of heating effect of electric 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:


What is Joule’s heating effect? How can it be demonstrated experimentally? List its four applications in daily life.


Match the following

1. Bulb a. Conductor
2. Electroplating b.

Insulator

3. Pure water c.  Heating effect of current
4. Salt solution d. Chemical effect of current

What is a trip switch?


The following is not a safety device.


An electric fuse is a wire made up of a material having ______ melting point.


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


Define the following:

Electrolyte


1 kWh is equal to ______.


What is the heating effect of electric current?


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