A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistance, which may be used separately, in series, or parallel. What are the currents in the three cases?

Question:

Answer:

(i)Potential difference = 220 V,

resistance of each coil = 24 Ω

‍

(ii)When Coil A and B are connected in series :

R_s = r + r

= 2r

= 48Ω

Current flowing :

I_S = V/R_S

I_S = 220/48

I_S = 4.58 A

‍

(iii)When Coil A and B are connected in parallel :

R_P = r/2

R_P = 24/2

R_P= 12Ω

‍

Current flowing :

I_p = V/R_p

I_p = 220/12

I_p = 18.3Ω

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Several electric bulbs designed to be used on a 220 V electric supply line, are rated 10 W. How many lamps can be connected in parallel with each other across the two wires of a 220 V line if the maximum allowable current is 5 A?

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A copper wire has a diameter of 0.5 mm and resistivity of 1.6 × 10–8Ω m. What will be the length of this wire to make its resistance 10 Ω? How much does the resistance change if the diameter is doubled?

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Two conducting wires of the same material and equal lengths and equal diameters are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be : (a) 1 : 2 (b) 2 : 1 (c) 1 : 4 (d) 4 : 1

An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be : (a) 100 W (b) 75 W (c) 50 W (d) 25 W

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A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R’, then the ratio R/R’ is : (a) 1/25 (b) 1/5 (c) 5 (d) 25

An electric motor takes 5 A from a 220 V line. Determine the power of the motor and the energy consumed in 2 h

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

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Redraw the circuit of Question 1, putting in an ammeter to measure the current through the resistors and a voltmeter to measure the potential difference across the 12 W resistor. What would be the readings in the ammeter and the voltmeter?

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Chapter 11 NCERT Class 10 Science SOLUTIONS

Question:

Answer:

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Chapter 11 NCERT Class 10 Science SOLUTIONS

Question:

Answer:

More NCERT Questions

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

Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?

Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to the electric mains supply. What current is drawn from the line if the supply voltage is 220 V?

Compare the power used in the 2 Ω resistor in each of the following circuits: (i) A 6 V battery in series with 1 Ω and 2 Ω resistors. (ii) A 4 V battery in parallel with 12 Ω and 2 Ω resistors.

Several electric bulbs designed to be used on a 220 V electric supply line, are rated 10 W. How many lamps can be connected in parallel with each other across the two wires of a 220 V line if the maximum allowable current is 5 A?

Show how you would connect three resistors, each of resistance 6 Ω so that the combination has a resistance of (i) 9 Ω, (ii) 4 Ω.

A battery of 9 V is connected in series with resistors of 0.2 Ω, 0.3 Ω, 0.4Ω, 0.5Ω and 12Ω, respectively. How much current would flow through the 12Ωresistor?

A battery of 9 V is connected in series with resistors of 0.2 Ω, 0.3 Ω, 0.4Ω, 0.5Ω and 12Ω, respectively. How much current would flow through the 12Ωresistor?

When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.

The values of current I flowing in a given resistor for the corresponding values of potential difference V across the resistor are given below : I (amperes) 0.5 1.0 2.0 3.0 4.0 V (volts) 1.6 3.4 6.7 10.2 13.2 Plot a graph between V and I and calculate the resistance of that resistor.

A copper wire has a diameter of 0.5 mm and resistivity of 1.6 × 10–8Ω m. What will be the length of this wire to make its resistance 10 Ω? How much does the resistance change if the diameter is doubled?

How is a voltmeter connected in the circuit to measure the potential difference between two points?

Two conducting wires of the same material and equal lengths and equal diameters are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be : (a) 1 : 2 (b) 2 : 1 (c) 1 : 4 (d) 4 : 1

An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be : (a) 100 W (b) 75 W (c) 50 W (d) 25 W

Which of the following terms does not represent electrical power in a circuit? (a) I2R (b) IR2 (c) VI (d) V2/R [NCERT]

A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R’, then the ratio R/R’ is : (a) 1/25 (b) 1/5 (c) 5 (d) 25

An electric motor takes 5 A from a 220 V line. Determine the power of the motor and the energy consumed in 2 h

What determines the rate at which energy is delivered by a current

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

Compute the heat generated while transferring 96000 Coulomb of charge in one hour through a potential difference of 50 V.

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

What is (a) the highest, (b) the lowest total resistance that can be secured by combinations of four coils of resistance 4 Ω, 8 Ω, 12 Ω, 24 Ω?

How can three resistors of resistances 2 Ω, 3 Ω and 6 Ω be connected to give a total resistance of (a) 4 Ω, (b) 1 Ω

What are the advantages of connecting electrical devices in parallel with the battery instead of connecting them in series?

Judge the equivalent resistance when the following (a) 1 Ω and 106 Ω, (b) 1 Ω and 103 Ω and 106 Ω.

Redraw the circuit of Question 1, putting in an ammeter to measure the current through the resistors and a voltmeter to measure the potential difference across the 12 W resistor. What would be the readings in the ammeter and the voltmeter?

Draw a schematic diagram of a circuit consisting of a battery of three cells of 2 V each, a 5 W resistor, an 8 W resistor, and a 12 W resistor, and a plug key, all connected in series.

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