Electric Power | Electricity | Assessment | English | Grade 10

What is the value of 1 unit of electricity we pay for?

• 3.6 × 10⁶ J

• 1 kW

• 1 Wh

• 3.6 × 10⁶ Js

Answer explanation

The commercial unit of electricity is basically energy we consumed as 1 unit which is equivalent to 1 kWh. 1 kWh = 1000W × 3600s = 3.6 × 10⁶ J

Tags

NGSS.HS-PS2-5

Choose the odd one out.

• VI

• I²R

• V²/R

• IR

Answer explanation

First three the various forms to write Power. The last one is the representation of potential difference.

An iron having a power of 1.6 kW. How much energy will it consume if we operate it for half an hour?

• 3.6 × 10⁶ J

• 2.88 × 10⁶ J

• 1.6 kWh

• 1 commercial unit of electrical energy

Answer explanation

Power (P) = 1.6 kW Time (t) = 0.5 hours Heat (H) = P×t = 1.6 kW × 0.5 h = 0.8 kWh = 0.8 ×3.6 × 10⁶ J = 2.88 × 10⁶ J

Tags

NGSS.HS-PS3-1

An electric bulb having rating of 100 W is enlighten for 8 hours a day. If the cost per unit of electricity is INR 7. Then what will the amount charged against this bulb in the monthly electricity bill of January?

• INR 56

• INR 5600

• INR 173600

• INR 173.6

Answer explanation

Power (P) = 100 W Time per day (t) = 8 hours Energy consumed in one day (h)= P×t = 100 × 8 = 800 Wh No. of days in January = 31 Total Energy consumed (H) = h × 31 = 800 × 31 = 24,800 Wh = 24.8 kWh Cost of 1 unit (1 kWh) = 7 Total cost = 24.8 × 7 = INR 173.6