An object is placed at the centre of curvature of a concave mirror. The image formed is MCQ with Answer and Explanation

Explanation:
A transformer core is subject to alternating magnetic fields, tracing out a hysteresis loop repeatedly. To minimize energy loss (hysteresis loss), the area of this loop must be small, requiring low coercivity (easily demagnetized). It also requires low retentivity so it loses magnetism rapidly when current stops. Steel, conversely, has high retentivity and coercivity, used for permanent magnets.

Explanation:
Geostationary satellite has orbital period equal to Earth's rotation (24 hours) and orbits in equatorial plane in same direction. It appears stationary from Earth's surface. Altitude about 36,000 km. Used for communication.

Explanation:
Constant velocity ⇒ no change in speed or direction ⇒ acceleration = dv/dt = 0. Newton's first law: zero net force for constant velocity. Memory tip: 'Constant v ⇒ a = 0; changing v ⇒ a ≠ 0'. Basic kinematics concept frequently tested to verify acceleration-velocity relationship understanding.