Advertisements
Advertisements
Question
An electric bulb is rated 250 W, 230 V.
- the energy consumed in one hour, and
- the time in which the bulb will consume 1.0 kWh energy when connected to 230 V mains.
Solution
(i) Given, Power (P) = 250 W, Voltage (V) = 230 V, Time (t) = 1 h = 3600 sec, Energy (E) = ?
Energy, E = P × t
Substituting the values in the formula above, we get,
E = 250 × 3600
E = 9 × 105 J
(ii) Let t be the time in which the bulb will consume 1.0 kWh energy when connected to 230 V mains.
P = 1.0 kWh = 1000 Wh
Substituting the value in the formula, we get,
⇒ 1000 = 250 × t
⇒ t = `1000/250`
⇒ t = 4 h
Hence, time = 4 h
APPEARS IN
RELATED QUESTIONS
One coulomb charge is equivalent to the charge contained in:
(a) 2.6 × 1019 electrons
(b) 6.2 × 1019 electrons
(c) 2.65 × 1018 electrons
(d) 6.25 × 1018 electrons
Which particles constitute the electric current in a metallic conductor?
A 5 V battery is connected to two 20 Ω resistors which are joined together in series.
(a) Draw a circuit diagram to represent this. Add an arrow to indicate the direction of conventional current flow in the circuit.
(b) What is the effective resistance of the two resistors?
(c) Calculate the current that flows from the battery?
(d) What is the p.d. across each resistor?
Tick(✓) the correct choice in the following:
The outer casing of an electric iron is generally connected to earth in order
to
An electric bulb is rated at 220 V, 100 W.
- What is its resistance?
- What safe current can be passed through it?
Explain, why the potential difference across the terminals of a cell is more when the cell is not in use than it is when the cell is being used.
Define an electric current.
Coulomb is the SI unit of ____________.
