1.

An electron is moving with a velocity (2 hat(i) + 2hat(j))m//s is an electric field of intensity vec(E )= hat(i) + 2hat(j)- 8 hat(k) V//m and a magnetic field of vec(B)= (2 hat(j) + 3hat(k)) tesla. The magnitude of force on the electron is

Answer»

`14.4 xx 10^(-19)N`
`9 xx 10^(-19)N`
`11.2 xx 10^(-19)N`
`6.4 xx 10^(-19)N`

Solution :Here, velocity of electron `=VEC(V) = 2 hat(i)+ 2hat(j)ms^(-1)`
Electric field `= vec(E )= hat(i) + 2hat(j) - 8hat(k) V m^(-1)`
Magnetic field `= vec(B) = 2hat(j) + 3HAT(k) T`
`:.` The Lorentz FORCE is
`vec(F) = q (vec(E ) + vec(v) xx vec(B))`
`=(-1.6 xx 10^(-19)) [hat(i) + 2hat(j) -8hat(k) + (2hat(i) + 2hat(j)) xx (2hat(j) + 3hat(k))]`
`=(-1.6 xx 10^(-19)) [hat(i) + 2hat(j) - 8hat(k) + 4hat(k) - 6hat(j) + 6hat(i)]`
`=(-1.6 xx 10^(-19)) [7 hat(i) - 4hat(j) - 4hat(k)]`
`|vec(F)| = 1.6 xx 10^(-19) xx 9 = 14.4 xx 10^(-19)N`


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