Exercise

Which electrical device do we use to know whether current is flowing in a circuit or not and in which direction?

Write the laws of refraction of light.

Write the Ohm's law for an electric circuit. Also write the necessary formula for it.

Write down the Fleming's left-hand rule and draw the necessary diagram to explain the direction of force acting on it when a current-carrying rod is placed vertically in a magnetic field. 

What do you understand by magnetic field? Write the characteristics of magnetic field lines of force. Draw the necessary diagram to show the magnetic field produced by a current carrying circular coil.

What is the working principle of an electric motor? Explain the working of it by drawing the necessary diagram. Also write down two uses of electric motor.

Using a concave mirror of focal length $15 \mathrm{cm}$, we want to form an erect image of an object. What should be the range of distance of the object from the mirror. Write a note on the nature and size of the image. Draw a ray diagram of the image formation in this situation. The magnification produced by a mirror is $+1$. What is it meaning ?

If three resistors $2 \mathrm{\Omega }, 3 \mathrm{\Omega }, 6 \mathrm{\Omega }$ are connected in parallel, then calculate the equivalent resistance of this combination.