The time period of a mass-spring system depends on MCQ with Answer and Explanation

Explanation:
Steel has high retentivity, retains magnetism, used for permanent magnets. Soft iron has low retentivity, used for electromagnet core (temporary). Alnico, ferrites also used.

Explanation:
Potentiometer sensitivity (ability to detect small EMF changes) increases with longer wire because potential gradient (V/cm) decreases, allowing finer measurement of balancing length. Sensitivity ∝ length of wire. Decreasing length (B) reduces sensitivity; increasing current (C) increases potential gradient, reducing sensitivity; thicker wire (D) reduces resistance but doesn't directly affect sensitivity if current adjusted. Memory tip: 'Longer potentiometer wire ⇒ smaller potential gradient ⇒ higher sensitivity'. This experimental physics concept is frequently tested in competitive exams. Always link sensitivity to potential gradient: smaller gradient allows detection of smaller voltage differences.

Explanation:
Power = work done per unit time = kinetic energy imparted per second. KE per bullet = ½mv² = ½×0.01×(600)² = 1800 J. Bullets per second = 60/60 = 1. Thus power = 1800 J/s = 1800 W. Note: Mass conversion: 10 g = 0.01 kg. This problem combines kinetic energy formula with power definition. Exam tip: Always convert to SI units first (grams to kg, minutes to seconds). Such numerical problems test multi-step calculation skills and unit conversion proficiency essential for competitive examinations.