In a certain circuit current changes with time according to i = 2√t r.m.s. value of current between t = 2 to t = 4s will be
−i2=∫ i2dt∫ dt=∫42(4t)dt∫42dt=4∫42t dt2=2[t22]42=[t2]42=12 ⇒ irms=√−i2=√12=2√3A