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

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? - Science and Technology 1

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प्रश्न

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?

संख्यात्मक
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उत्तर

Given: Power, P = 100 W

Current, I = 3 A

Resistance, R = ?

We know, P = I2R

⇒ R = `P/I^2`

= `100/3^2`

= `100/9`

= 11.11 Ω

∴ The value of the resistance is 11.11 Ω.

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पाठ 4: Effects of electric current - Exercises [पृष्ठ ६१]

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बालभारती Science and Technology 1 [English] Standard 10 Maharashtra State Board
पाठ 4 Effects of electric current
Exercises | Q 12.1 | पृष्ठ ६१

संबंधित प्रश्‍न

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


Name any two effects of electric current.


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


An electric room heater draws a current of 2.4 A from the 120 V supply line. What current will this room heater draw when connected to 240 V supply line?


Explain why, the current that makes the heater element very hot, only slightly warms the connecting wires leading to the heater.


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


The current passing through a room heater has been halved. What will happen to the heat produced by it?


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


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


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. 


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 reason.

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


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).


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.


Answer the following question:
what is the heating effect of the electric current? state any four applications of it?


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


The ‘live’ and the ‘neutral’ wires have potential difference of _______.


The electricity bill specifies the usage in _______.


What does overloading cause?


Explain the heating effect of electric current.


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


Which of the following is correct?


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 component used as a safety device is electric circuit is ______.


Name two electric devices for each where

  1. heating effect of current is used and
  2. magnetic effect of current is used.

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


Name a few appliances which work on the basis of the heating effect of current.


What is a trip switch?


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


The electric fuse works on the Joule heating principle.


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?

Find the odd one out.


1 kWh is equal to ______.


In the electric equipment producing heat like iron, electric heater, boiler, toaster etc., an alloy such as nichrome is used, not pure metals.


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.


An electric iron is rated 220 V, 2 kW. If the iron is used for 3h daily find the cost of running it for one week if it costs ₹ 4.25 per kWh.


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