1.

Figure shows a conducting rod of negligible resistance that can slide on smooth U-shaped rail made of wire of resistance `1Omega//m`. Position of the conducting rod at `t=0` is shown. A time dependent magnetic field `B=2t` tesla is switched on at `t=0` At `t=0`, when the magnetic field is switched on, the conducting rod is moved to the left at constant speed `5cm//s` by some external means. At `t=2s`, net induced emf has magnitudeA. `0.12V`B. `0.12V`C. `0.04V`D. `0.02V`

Answer» Correct Answer - B
At `t=2s,` rod will move `10cm`. Hence `40cm` side will become `30cm`.
`|e|=e_1(say)=S((dB)/(dt))`
`(0.2xx0.3)(2)=0.12V`
At `t=2s, B=4T`
`:. e_2=Bvl`
`=(4)(5xx10^-2)(0.2)`
`=0.04V`
`:. e_("net")=e_1-e_2=0.08V`


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