समान त्रिज्या 2π cm वाले दो संकेंद्री लूप A और B एक-दूसरे के लंबवत रखे गए हैं। यदि A और B में प्रवाहित होने वाली धाराएं क्रमशः 3 A और 4 A हैं, तो उनके उभयनिष्ठ केंद्र पर कुल चुंबकीय क्षेत्र कितना होगा?

A solenoid of length 0.4 m having 500 turns of wire carries a current of 3 A. A thin coil having 10 turns of wire and radius 0.1 m carries a current of 0.4 A. The torque required to hold the coil in the middle of the solenoid with its axis perpendicular to the axis of the solenoid is (Take μ0 = 4π × 10-7 SI units, π2 = 10, sin(90°) = 1):

An electron makes one full rotation in a circular path of radius 0.8 m in one second. The magnetic field at the centre of the circle is: (μ0 = 4π × 10-7 T·m/A)