Work Calculation for Electric Bulb
The question asks for the amount of work done by an electric bulb given its power rating and the time duration.
Physics Formula
Power ($P$) is defined as the rate at which work ($W$) is done, or energy is transferred, over time ($t$). The formula is:
$ P = \frac{W}{t} $
To find the work done ($W$), we can rearrange the formula:
$ W = P \times t $
Applying the Values
We are given:
- Power ($P$) = 90 W
- Time ($t$) = 10 s
Substitute these values into the rearranged formula:
$ W = 90 \text{ W} \times 10 \text{ s} $
$ W = 900 \text{ J} $
The unit of work is Joules (J).
Conclusion
Therefore, the electric bulb does 900 Joules of work in 10 seconds. This matches Option A.
Important Questions from Work, Energy, and EMF
Which of the following is NOT a true difference between EMF and potential difference (PD)?
A battery of EMF 6.0 V and internal resistance 1.0 Ω is connected to a resistor of 11 Ω. The terminal potential difference for the battery is:
Consider two cells of emf ε1 and ε2 with internal resistances r1 and r2, respectively. The two cells are connected in parallel by connecting their positive terminals together and connecting their negative terminals together. The combination is equivalent to a single cell with emf given by:
Two batteries, E1 (emf: 3 V, internal resistance: 0.5 Ω) and E2(emf: 6 V, internal resistance: 1.0 Ω), are connected in series by connecting the positive terminal of E2 to the negative terminal of E1 . A third battery E3 (emf: 6 V, internal resistance: 1.0 Ω) is connected in parallel with this combination by connecting its positive terminal to the positive terminal of E1 and its negative terminal to the E2. The equivalent emf of this combination is:
- Two batteries E 1 (emf: 6 V, internal resistance: 0.5 Ω ) and E 2 (emf: 12 V, internal resistance: 1.0 Ω ) are connected in parallel by connecting their positive terminals to point A and negative terminals to point B. A third battery E 3 [emf: 6 V, internal resistance: ( \(\frac{2}{3}\) ) Ω ] is connected in series with this combination by connecting its positive terminal to B. The equivalent emf of this combination is
