Electric current and circuit
Electric Potential and Potential Difference
Circuit Diagram
Ohm's Law
Factors on which the resistance of a conductor depends
Resistance of a system of resistors
Resistors in series
Resistors in parallel
Heating effect of electric current
Practical Applications of heating effect of electric current
Electric Power
Questions Answers
NCERT Textbook.
1. What does an electric circuit mean?
Answer
An electric circuit is pathway in which current can follow. A circuit has electric devices, switching devices, source of energy etcetera. These are connected by conducting wire.
2. Define the unit of current.
Answer
When 1C of charge flows through a conductor in 1 s, it is called 1 ampere(A) current.
I = Q/t
The unit of electric current is ampere (A).
3. Calculate the number of electrons constituting one coulomb of charge.
Answer
We know that one electron possesses 1.6×10–¹⁹ C.
Therefore,
Number of electron = Total charge/Charge on 1 electron
or, No. of electron = 1/1.6×10–¹⁹
or, No. of electron = 6.25×10¹⁸ electrons. Ans.
1. Name a device that helps to maintain a potential difference across a conductor.
Answer
A cell, battery, power supply, etc helps to maintain potential difference across a conductor.
2. What is meant by saying that the potential difference between two points is 1 V?
Answer
When 1 J of work is required to move a charge of 1 C from one point to another, then it is said that the potential difference between two points is 1 V.
V = W/Q
or, 1 V = 1J/1C
3. How much energy is given to each coulomb of charge passing through a 6 V battery?
Answer
From question it is clear that
Work done = ?
Potential difference = 6 V
Charge = 1C.
We know that
Potential difference = Work done/Charge
Therefore,
Work done = Potential difference × Charge
or, Work done = 6 V×1C = 6 Joules Ans.
4. 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 combination would be
(a) 1:2
(b) 2:1
(c) 1:4
(d) 4:1
Answer
According to combination of resistance we know that
In the case of series
R(ES) = R1 + R2
From question it is clear that
R1 = R2 = R
R(S) = 2R
Similarly,
In the case of parallel
1/R(P) = 1/R1 + 1/R2
1/R(P) = 1/R + 1/R
R(P) = R/2
For same potential difference V,
We know that
V = IR
I = V/R
I(S) = V/R(S) = V/2R
Similarly,
I(P) = V/R(P) = 2V/R
H = I^2RT
Here,
I = Current follow through the conductor
R = Resistance
T = Time
Therefore,
H(S) = (V/2R)^2.R.T = V^2T/4R ------- (i)
Similarly,
H(P) = (2V/R)^2 . R.T = 4V^2T/R ------- (ii)
Now, from (i) and (ii)
Therefore, ratio of heat produced in series and parallel
H(S)/H(P) = 1:4 Ans.
Continues
Answers of the rest questions.....
