Download App

Alternating Current — Physics STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 SciencePhysicsAlternating Current2 Marks
Question
A light bulb and an open coil inductor are connected to an ac source through a key as shown in Fig. 7.9.
Image
The switch is closed and after sometime, an iron rod is inserted into the interior of the inductor. The glow of the light bulb (a) increases; (b) decreases; (c) is unchanged, as the iron rod is inserted. Give your answer with reasons.
✓

Answer

As the iron rod is inserted, the magnetic field inside the coil magnetizes the iron increasing the magnetic field inside it. Hence, the inductance of the coil increases. Consequently, the inductive reactance of the coil increases. As a result, a larger fraction of the applied ac voltage appears across the inductor, leaving less voltage across the bulb. Therefore, the glow of the light bulb decreases.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "2 Marks Questions" from Alternating Current→Alternating Current — all question types→Physics STD 12 Science question papers→Rajasthan Board STD 12 Science question papers→Rajasthan Board question paper generator→

Similar questions

Calculate the value of $i$ as shown in the figure.
Image
→
A man of mass $50\ kg$ starts moving on the earth and acquires a speed of $1.8\ m/s.$ With what speed does the earth recoil? Mass of earth $= 6 \times 10^{24}kg.$
→
Calculate the dimensions of:
  1. $\int\vec{\text{E}}.\vec{\text{dl}}.$
  2. $\text{vBl}$
  3. $\frac{\text{d}\psi_{\text{B}}}{\text{dt}}$
The symbols have their usual meanings.
→
In a resonance column experiment, a tuning fork of frequency 400Hz is used. The first resonance is observed when the air column has a length of 20.0cm and the second resonance is observed when the air column has a length of 62.0cm.
  1. Find the speed of sound in air.
  2. How much distance above the open end does the pressure node form?
→
Distinguish between 'intrinsic' and 'extrinsic' semiconductors.
→
Consider a gold nucleus to be a sphere of radius 6.9 fermi in which protons and neutrons are distributed. Find the force of repulsion between two protons situated at largest separation. Why do these protons not fly apart under this repulsion?
→
Give the information about charge and atomic number of the nucleus.
→
State the sign convention for applying Kirchhoff's loop rules.
→
A boy is standing on a platform which is free to rotate about its axis. The boy holds an open umbrella in his hand. The axis of the umbrella coincides with that of the platform. The moment of inertia of ''the platform plus the boy system'' is $3.0 \times 10^{-3}kg-m^2$ and that of the umbrella is $2.0 \times 10^3\ kg-m^2$. The boy starts spinning the umbrella about the axis at an angular speed of $2.0\ce{rev/s}$ with respect to himself. Find the angular velocity imparted to the platform.
→
Answer the following questions: In viewing through a magnifying glass, one usually positions one's eyes very close to the lens. Does angular magnification change if the eye is moved back?
→