Check sibling questions

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).

CA Maninder Singh's photo - Co-founder, Teachoo

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CA Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 12 years and a teacher from the past 16 years. He teaches Science, Economics, Accounting and English at Teachoo