Reason $(R):$ Opposite currents carrying wires repel each other.
$1^{st}$ Way : By using spring of smaller torsion constant.
$2^{nd}$ Way : By using a smaller coil
$3^{rd}$ Way : By using a stronger magnet
$4^{th}$ Way : By using a coil having fewer number of turns.

Assertion $(A)$ : In an uniform magnetic field, speed and energy remains the same for a moving charged particle.
Reason $(R)$ : Moving charged particle experiences magnetic force perpendicular to its direction of motion.