Question Discussion & Solution

• Power: The rate of work done by the electric energy is called power. It is denoted by P.
  • The SI unit of power is the watt (W).
  • Watt is a small unit that's why kilowatt-hour is used as the unit for electrical energy.
• 1 unit of electric energy: When one-kilowatt load works for 1 hour then the energy consumed is called 1 unit of electricity.

1 Unit of electricity = 1 kWh = 1000 Watt-hour = 3.6 × 106 J

1 Kilo-watt = 1000 Watt

• 1 Watt: The energy consumption rate of 1 joule per second is called 1 watt.

EXPLANATION:

Since 1 hr = 3600 sec

1 kWh = 1000 W-hr = 1000 × 3600 watt sec = 3.6 × 10⁶ J 

​So option 1 is correct.

CONCEPT:

• The battery has two terminals positive and negative and its positive terminal is the cathode and its negative terminal is the anode.
  • It works on the principle of Electrochemical Reaction.
  • Italian physicist Alessandro Volta built and described the first electrochemical battery, the voltaic pile, in the year 1800.
  • The lead-acid batteries used in vehicles and lithium-ion batteries used for portable electronics such as laptops and mobile phones.

EXPLANATION:

• A battery converts chemical energy into electrical energy. So option 3 is correct.

Given: Victory ∶ Encouragement ∶∶ Failure ∶ ?

Logic:

Victory leads to Encouragement.

Similarly,

Failure leads to Frustration.

Hence, frustration is the correct answer.

All given numbers are cube except 400. 400 is a square of 20.

The correct answer is Element.

Key Points

• An electric room heater or an electric heater used for cooking contains a coil of wire.
• The coil of wire used in electric heaters is called a heating element.
• The heating coil of the electric room heater transfers the electric energy into heat energy.
• The elements become red hot and give out heat after connecting to the electric supply.
• The amount of heat produced in a wire depends on its material used, length, and thickness.
• The coil of the electric heater is made up of nichrome.
• Nichrome consists of 80% nickel, 20% chromium.

Additional Information

• The filament is usually made of very thin tungsten wire.
  • In an incandescent bulb, an electric current is passed through a metal filament.
• A cell is a single unit device that converts chemical energy into electric energy.
  • It produces electricity capable to run smaller appliances.
• A battery usually consists of a group of cells.

Mistake Points

• A filament is a fine resistance wire the purpose of which is to emit white light. 
• An element is a resistive wire the sole purpose of which is to produce heat.