Change set

Pick exam & year, then Go.

Question map
Not attempted Correct Incorrect ★ Bookmarked
Loading…
Q91 (NDA-II/2011) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Electricity and magnetism Answer Verified

An electric lamp of 100 watt is used for 10 hours per day. The ‘units’ of energy consumed in one day by the lamp is

Result
Your answer: —  ·  Correct: A
Explanation

The energy consumed by an electrical appliance is calculated by multiplying its power rating by the time it is used. In this case, the electric lamp has a power of 100 watts (W) and is used for 10 hours (h) per day. The total energy consumed in one day is 100 W × 10 h = 1,000 watt-hours (Wh) [t3]. The commercial unit of electrical energy is the kilowatt-hour (kWh), which is commonly referred to as a 'unit' [c1][c2]. Since 1 kilowatt (kW) equals 1,000 watts, 1,000 Wh is equivalent to 1 kWh (1,000 Wh / 1,000 = 1 kWh) [t2][t7]. Therefore, a 100-watt lamp operating for 10 hours consumes exactly 1 unit of electricity [t2][t6]. This standard conversion is fundamental for utility billing and energy management [t1].

Sources

  1. [1] Science , class X (NCERT 2025 ed.) > Chapter 11: Electricity > 11.8 ELECTRIC POWER > p. 191
  2. [2] Science , class X (NCERT 2025 ed.) > Chapter 11: Electricity > What you have learnt > p. 192
How others answered
Each bar shows the % of students who chose that option. Green bar = correct answer, blue outline = your choice.
Community Performance
Out of everyone who attempted this question.
0%
got it right
✓ Thank you! We'll review this.

SIMILAR QUESTIONS

CDS-I · 2023 · Q66 Relevance score: 6.70

A 100 W electric bulb is used for 10 hours a day. How many units of electrical energy are consumed by the bulb in 3 days? (1 unit = 1 kWh)

CDS-II · 2019 · Q9 Relevance score: 5.81

A 100 W electric bulb is used for 10 hours a day. How many units of energy are consumed in 30 days ?

NDA-I · 2008 · Q2 Relevance score: -1.80

The rating of an electric lamp is 110 V. To use it to 220 V, one will have to use which one of the following?

NDA-I · 2021 · Q97 Relevance score: -2.86

A current of 1.0 A is drawn by a filament of an electric bulb for 10 minutes. The amount of electric charge that flows through the circuit is

CDS-I · 2014 · Q83 Relevance score: -2.91

When an incandescent electric bulb glows