Question 2 - Case Based Questions (MCQ) - Chapter 12 Class 10 - Electricity

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).