Resistance: Electric Current and Potential Difference

What happens to resistance of a conductor when its area of cross-section is increased?
Ans.
Resistance decreases

Question 2
The charge possessed by an electron is 1.6x10-19 coulombs. Find the number of electrons that will flow per second to constitute a current of 1 ampere.
Ans.

Question 3
Name the instrument used to measure electric current in a circuit.
Ans.
Ammeter

Question 4
In the following table the values of current I flowing in a given resistor for the corresponding values of potential difference V across the resistor are shown : 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 use this graph to find the value of current when potential difference across the resistor is 5V.
Ans.

Finding the current corresponding to 5 V potential difference (from graph) =1.5 A (approx.)

Question 5
(a) What does the following circuit symbols represent?
(i) (ii)
(b) The potential difference between the terminals of an electric heater is 60 V when it draws a current of 4 A from the source. Find the resistance of heater when in use.
Ans.
(a) (i) Wires not connected
(ii) Variable resistor/rheostat

Question 6
Mention any two factors on which the resistance of a cylindrical conductor depends.
Ans.
Its length, its cross sectional area, nature of its material and temperature of the conductor. (Any two)

Question 7
An electric heater draws a current of 10A when connected to a 200 V supply. What current will the heater draw when it is connected to 220 V supply.
Ans.

Question 8
How is an ammeter connected in a circuit to measure current flowing through it?
Ans.
In series.

Question 9
What is meant by the statement that the potential difference between two points is 1 volt?
Ans.
It means that one joule of work is done to move a charge of one coulomb from one point to another.

Question 10
Name the instrument used for