✓ Board-verified↻ asked 3×
Science · 2026 · 3 marks
CBSE 2026 · Region 5 · Set 1 · Q37
(a)Why does an electric bulb become dim when an electric heater in parallel circuit is switched ON ?(b)How to connect three resistors each of resistance $\displaystyle 8 \Omega$, so that the equivalent resistance of the combination is $\displaystyle 12 \Omega$ ? Draw diagram of the combination and justify your answer.
(a)
Why does an electric bulb become dim when an electric heater in parallel circuit is switched ON ?
(b)
How to connect three resistors each of resistance $\displaystyle 8 \Omega$, so that the equivalent resistance of the combination is $\displaystyle 12 \Omega$ ? Draw diagram of the combination and justify your answer.
Marking-scheme solution
(a)
When the electric heater is switched on in a parallel circuit, it
draws a large amount of current. As a result, the current through
the bulb decreases, making the bulb glow dim.
(b)
$\displaystyle \frac{1}{R_{1}}=\frac{1}{8}+\frac{1}{8}$
\[\begin{array}{l}
R_{1}=4 \Omega \\
R_{\mathrm{eq}}=R_{1}+8 \Omega \\
R_{\mathrm{eq}}=12 \Omega
\end{array}
\]
More from Electricity
- In domestic electric circuits the wiring with 15 A current rating is for the electric devices which have2023 · asked 3×
- Assertion: Electrons move from lower potential to higher potential in a conductor. Reason (R): A dry cell…2024 · asked 3×
- The resistance of a wire of 0.01 cm radius and 1.0 cm length is 7 Ω. Calculate its resistivity. OR An…2026 · asked 3×
- Four identical resistors of 12 Ω each are connected in series to form a square ABCD as shown in the figure.…2025 · asked 3×
- The resistance of a wire of 0.01 cm radius is 7 ohms. If the resistivity of the material of the wire is 44 ×…2025 · asked 3×
- Read the following passage and answer the questions that follow: Swati, a class 10 student, observes that…2026 · asked 3×
- For verifying Ohm's law, we design an electric circuit diagram in which we show the arrangement of different…2023 · asked 3×
- The minimum number of identical bulbs of rating 4V; 6W, that can work safely with desired brightness, when…2025 · asked 3×
CBSE Class 10 Science past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.