Class 10 Science - Chapter Electricity NCERT Solutions | Two conducting wires of the same materia
Two conducting wires of the same material and of 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
(c) The Joule heating is given by, H = i2Rt
Let, R be the resistance of the two wires.
The equivalent resistance of the series connection is RS = R + R = 2R
If V is the applied potential difference, then it is the voltage across the equivalent resistance.
The heat dissipated in time t is,
The equivalent resistance of the parallel connection is
V is the applied potential difference across this RP.
The heat dissipated in time t is,
So, the ratio of heat produced is,
Note: H 
also H i2 and H t. In this question, t is same for both the circuit. But the current through the equivalent resistance of both the circuit is different. We could have solved the question directly using H R if in case the current was also same. As we know the voltage and resistance of the circuits, we have calculated i in terms of voltage and resistance and used in the equation H = i2Rt to find the ratio.
More Questions From Class 10 Science - Chapter Electricity
- Q:-
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.
- Q:-
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 in parallel. What are the currents in the three cases?
- Q:-
Calculate the number of electrons constituting one coulomb of charge.
- Q:-
Explain the following.
(a) Why is the tungsten used almost exclusively for filament of electric lamps?
(b) Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
(c) Why is the series arrangement not used for domestic circuits?
(d) How does the resistance of a wire vary with its area of cross-section?
(e) Why are copper and aluminium wires usually employed for electricity transmission? - Q:-
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 220 V line if the maximum allowable current is 5 A?
- Q:-
An electric lamp of 100 Ω, a toaster of resistance 50 Ω, and a water filter of resistance 500 Ω are connected in parallel to a 220 V source. What is the resistance of an electric iron connected to the same source that takes as much current as all three appliances, and what is the current through it?
- Q:-
Let the resistance of an electrical component remains constant while the potential difference across the two ends of the component decreases to half of its former value. What change will occur in the current through it?
- Q:-
Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal?
- Q:-
How much energy is given to each coulomb of charge passing through a 6 V battery?
- Q:-
Draw a schematic diagram of a circuit consisting of a battery of three cells of 2 V each, a 5 Ω resistor, an 8 Ω resistor, and a 12 Ω resistor, and a plug key, all connected in series.
Popular Questions of Class 10 Science
- Q:-
Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
- Q:-
What is a good source of energy?
- Q:-
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
- Q:-
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
- Q:-
What changes can you make in your habits to become more environment-friendly?
- Q:-
What is the difference between a reflex action and walking?
- Q:-
What is the importance of DNA copying in reproduction?
- Q:-
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
- Q:-
Why should a magnesium ribbon be cleared before burning in air?
- Q:-
Define the principal focus of a concave mirror.
Recently Viewed Questions of Class 10 Science
- Q:-
Give an example of a plant hormone that promotes growth.
- Q:-
Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass? The speed of light in vacuum is 3 × 108 m s–1.
- Q:-
Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows.
Metal Iron(II) sulphate Cooper(II) sulphate Zinc sulphate Silver nitrate A No reaction Displacement B Displacement No reaction Displacement C No reaction No reaction No reaction No reaction - Q:-
How does the embryo get nourishment inside the mother’s body?
- Q:-
How would these advantages differ from the advantages of using a long-term perspective in managing our resources?
- Q:-
Draw a labelled diagram of the longitudinal section of a flower.
- Q:-
What are alloys?
- Q:-
What would you observe when zinc is added to a solution of iron(II) sulphate? Write the chemical reaction that takes place.
- Q:-
Explain the mechanism of the cleaning action of soaps.
- Q:-
The position of three elements A, B and C in the Periodic Table are shown below –
Group 16 Group 17
- -
- A
- -
B C(a) State whether A is a metal or non-metal.
(b) State whether C is more reactive or less reactive than A.
(c) Will C be larger or smaller in size than B?
(d) Which type of ion, cation or anion, will be formed by element A?
- All Chapters Of Class 10 Science
- All Subjects Of Class 10