Electric field in the region is given by $$\mathbf{E}=\left(M / x^4\right) \hat{\mathbf{i}}$$, then the correct expression for the potential in the region is (assume potential at infinity is zero)
The gravitational field in a region is given by $$\mathbf{E}=5 \mathrm{~N} / \mathrm{kg} \hat{\mathbf{i}}+12 \mathrm{~N} / \mathrm{kg} \hat{\mathbf{j}}$$. The change in the gravitational potential energy of a particle of mass $$1 \mathrm{~kg}$$ when it is taken from the origin to a point ($$5 \hat{\mathbf{i}}-5 \hat{\mathbf{j}}$$) is
Two parallel conductors carry current in opposite directions as shown in the figure. One conductor carries a current of $$20 \mathrm{~A}$$. Point $$C$$ is a distance $$d / 2$$ to the right of a 20 A current. If $$d=18 \mathrm{~cm}$$ and $$i$$ is adjusted so that the magnetic field at $$C$$ is zero, the value of the current $$i$$ is
The activity of a radioactive sample is measured as No counts per minute at $$t=0$$ and $$\mathrm{N}_0 / \mathrm{e}$$ counts per minute at $$t=6 \mathrm{~min}$$. The time (in minutes) at which the activity reduces to half its value is.