Download App

Electromagnetic Induction — JEE physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 ScienceJEE physicsElectromagnetic Induction1 Mark
Question
Assertion : A spark occur between the poles of a switch when the switch is opened.
Reason : Current flowing in the conductor produces magnetic field.
✓

Answer

(b) According to Lenz's law, induced emf are in a direction such as to attempt to maintain the original magnetic flux when a change occurs. When the switch is opened, the sudden drop in the magnetic field in the circuit induces an emf in a direction that attempts to keep the original current flowing. This can cause a spark as the current bridges the air gap between the poles of the switch. (The spark is more likely in circuits with large inductance).

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 "Assertion & Reason" from Electromagnetic Induction→Electromagnetic Induction — all question types→JEE physics STD 12 Science question papers→CBSE Board STD 12 Science question papers→CBSE Board question paper generator→

Similar questions

Assertion : A large soap bubble expands while a small bubble shrinks, when they are connected to each other by a capillary tube.
Reason : The excess pressure inside bubble (or drop) is inversely proportional to the radius.
→
Assertion : The position-time graph of a uniform motion in one dimension of a body can have negative slope.
Reason : When the speed of body decreases with time, the position-time graph of the moving body has negative slope.
→
Assertion : If the displacement of the body is zero, the distance covered by it may not be zero.
Reason : Displacement is a vector quantity and distance is a scalar quantity.
→
Assertion : When a bottle of cold carbonated drink is opened, a slight fog forms around the opening.
Reason : Adiabatic expansion of the gas causes lowering of temperature and condensation of water vapours.
→
Assertion : As the frictional force increases, the safe velocity limit for taking a turn on an unbanked road also increases.
Reason : Banking of roads will increase the value of limiting velocity.
→
Assertion : Steel is more elastic than rubber.
Reason : Under given deforming force, steel is deformed less than rubber.
→
Assertion : Work done by a gas in isothermal expansion is more than the work done by the gas in the same expansion, adiabatically.
Reason : Temperature remains constant in isothermal expansion and not in adiabatic expansion.
→
Assertion : Animals curl into a ball, when they feel very cold.
Reason : Animals by curling their body reduces the surface area.
→
Assertion $\quad$ : Vector addition is commutative.
Reason $\quad: \quad(\vec{A}+\vec{B}) \neq(\vec{B}+\vec{A})$.
→
Assertion : The viscosity of liquid increases rapidly with rise of temperature.
Reason : Viscosity of a liquid is the property of the liquid by virtue of which it opposes the relative motion amongst its different layers
→