JEE Main · 2022 · 27 Jun 2022 · Shift 1 · Current Electricity

WhatsApp Email

220 V, 50 Hz AC

source is connected to a 25 V , 5 W lamp and an additional resistance R in series (as shown in figure) to run the lamp at its peak brightness, then the value of R (in ohm) will be ____。

Answer: 975

Solution

For the lamp to run at peak brightness, it must operate at rated values:

P = 5

V = 25

V. Current through lamp:

i = \frac{P}{V} = \frac{5}{25} = 0.2

A. Voltage across R:

V_{R} = 220 - 25 = 195

V. Therefore

R = \frac{V _{R}}{i} = \frac{195}{0.2} = 975

Ω.

JEE Main · 2022 · 27 Jun 2022 · Shift 1 · Integer answer

Practise more: all JEE Main PYQs on Current Electricity →

More JEE Main questions on Current Electricity

A meter bridge with two resistances $R_{1}$ and $R_{2}$ as shown in figure was balanced (null point) at 40 cm from the point P. The null point changed to 50 cm from the point P, when $16Ω$ resistance is connected in parallel to $R_{2}$ . The values of resistances $R_{1}$ and $R_{2}$ ar …
JEE Main 2026View solution →
An electric power line having total resistance of $2Ω$ , delivers 1 kW of power of 250 V. The percentage efficiency of transmission line is $____$ .
JEE Main 2026View solution →
A cylindrical conductor of length 2 m and area of cross-section $0.2 mm^{2}$ carries an electric current of 1.6 A when its ends are connected to a 2 V battery. Mobility of electrons in the conductor is $α \times 1 0^{- 3} m^{2} / V$ .s. The value of …
JEE Main 2026View solution →
The charge stored by the capacitor C in the given circuit in the steady state is $____$ $μ C$ .
JEE Main 2026View solution →
The total length of potentiometer wire AB is 50 cm in the arrangement as shown in figure. If P is the point where the galvanometer shows zero reading then the length AP is $____$ cm .
JEE Main 2026View solution →
A battery with EMF E and internal resistance $r$ is connected across a resistance $R$ . The power consumption in R will be maximum when :
JEE Main 2026View solution →