Study the given table and answer any four questions from (a) to (e):
Question 2(a)
Which is a better conductor:
(i) Chromium
(ii) Nickel
(iii) Mercury
(iv) Iron
Answer:
The property of the conductor which resists the flow of electric current is called resistivity.
So, lower the resistivity, better the conductivity.
Checking the options:
- (i) Chromium
- (ii) Nickel - Least resistivity
- (iii) Mercury
- (iv) Iron
So, the correct answer is (ii).
Question 2( b)
Element used to make heating element of electric geyser:
(i) Iron
(ii) Silver
(iii) Nichrome
(iv) tungsten
Answer:
The element used for making heating elements should have high resistivity so that it can hold its configuration in a high voltage current.
Checking the options:
- (i) Iron
- (ii) Silver
- (iii) Nichrome - Highest resistivity
- (iv) tungsten
So, the correct answer is (iii).
Question 2(c)
Element used to make filament of incandescent bulb:
(i) Copper
(ii) Silver
(iii) Nichrome
(iv) tungsten
Answer:
Element used to make filament of incandescent bulb should have high resistivity and high melting point.
Checking the options:
- (i) Copper - Low resistivity
- (ii) Silver - Low resistivity
- (iii) Nichrome - High resistivity
- (iv) tungsten - High resistivity and high melting point.
So, the correct answer is (iv)
Question 2(d)
What happens to resistance of a conductor when its area of cross section is increased?
(i) Resistance increases
(ii) Resistance decreases
(iii) No change
(iv) Resistance doubles
Answer:
Resistance of a conductor is inversely proportional to area of cross section.
So, if the area of the cross section increases , resistance decreases.
So, the correct answer is (ii).
