मराठी
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?

Advertisements
Advertisements

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
Advertisements

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.

shaalaa.com
  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 4: Effects of electric current - Exercise [पृष्ठ ६१]

APPEARS IN

बालभारती Science and Technology Part 1 [English] Standard 10 Maharashtra State Board
पाठ 4 Effects of electric current
Exercise | Q 12. a. | पृष्ठ ६१

संबंधित प्रश्‍न

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


Why is the tungsten used almost exclusively for filament of electric lamps?


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.


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?


An electric iron of resistance 20 ohms draws a current of 5 amperes. Calculate the heat produced in 30 seconds.


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


What is meant by the 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 × 


The electrical resistivities of four materials P, Q, R and S are given below:

P `6.84xx10^8`Ωm
Q `1.70xx10^8`Ωm  
R ` 1.0xx10^15`Ωm
s  `11.0xx10^-7`Ωm  

Which material will you use for making: (a) heating element of electric iron (b) connecting wires of electric iron (c) covering of connecting wires? Give reason for your choice in each case.

 


Give a scientific reason.

Tungsten metal is used to make a solenoid type coil in an electric bulb.


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 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.


Rewrite the following statement by selecting the correct option:

1 A = ____________ mA.


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


Find the odd one out and give its explanation.


Explain the importance/uses of fuse wire.


Explain the application of heating effect of electric current in an electric bulb with a diagram.


True or False – If False give the correct answer

The fuse wire does not melts whenever there is overload in the wiring.


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 bulb is connected to a 220 V generator. The current is 0.50 A. What is the power of the bulb?


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?


B1, B2 and B3 are three identical bulbs connected as shown in Figure. When all the three bulbs glow, a current of 3A is recorded by the ammeter A.

  1.  What happens to the glow of the other two bulbs when the bulb B1 gets fused?
  2. What happens to the reading of A1, A2, A3 and A when the bulb B2 gets fused?
  3. How much power is dissipated in the circuit when all the three bulbs glow together?

 


(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).


When a switch is in OFF position,

  1. circuit starting from the positive terminal of the cell stops at the switch.
  2. circuit is open.
  3. no current flows through it.
  4. current flows after some time. 

Choose the combination of correct answer from the following.


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


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.

  1. Will the heat produced in both cases be equal? Explain.
  2. Will the heat produced be the same if the wires taken by them are of equal lengths but of different thickness? Explain.


______ wire is used in the filament of the bulbs.


Fuse is a strip of alloy wire which is made up of lead and tin with a very low ______.


Name the effect of the current responsible for the glow of the bulb in an electrical circuit.


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


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.


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?

An electric kettle of 2 kW is used for 2h. Calculate the energy consumed in 

  1. kilowatt hour and
  2. joules.

The graph of voltage vs current for four different materials is shown below.

Which of these four materials would be used for making filament of bulb?


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×