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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

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.


How does the resistance of a wire vary with its area of cross-section?


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?


Give two reasons why nichrome alloy is used for making the heating elements of electrical appliances.


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


Explain why, tungsten is used for making the filaments of electric bulbs.


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.


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


Which of the following substance contracts on heating?


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


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


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


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


A current of 1 A is drawn by a filament of an electric bulb. Number of electrons passing through a cross-section of the filament in 16 seconds would be roughly:


Why is parallel arrangement used in domestic wiring?


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?

 


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


An electric fuse has a body made of ceramic and two points for connecting the fuse wire.


What are the uses of electromagnets?


What is an electric fuse made up of?


Explain the working of an electric fuse.


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Reason: The current in a wire is due to the flow of free electrons in a definite direction.


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


The following is not a safety device.


A trip switch is a ______ safety device.


A fuse is used in an electric circuit to stop high currents flowing through the circuit.


Two students decided to investigate the effect of water and air on iron object under identical experimental conditions. They measured the mass of each object before placing it partially immersed in 10 ml of water. After a few days, the object were removed, dried and their masses were measured. The table shows their results.

Student Object Mass of Object
before Rusting in g
Mass of the coated
object in g
A Nail 3.0 3.15
B Thin plate 6.0 6.33

What might be the reason for the varied observations of the two students?


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.


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.


When a current I flows through a wire of resistance R for time t then the electrical energy produced is given by ______.


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?


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