Case Based Questions (MCQ)

Class 10
Chapter 12 Class 10 - Electricity

## (iv) Iron

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).

## (iv) tungsten

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).

## (iv) tungsten

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)

## (iv) Resistance doubles

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).

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