Who discovered the electron?

An electric refrigerator rated $400 \ W$ operates $8 \ h$ per day. What is the cost of the energy to operate it for $30$ days at ₹ $3.00$ per $kWh$?

Who invented the simple battery?

An electric oven hot plate is connected to a $200 \, V$ line. It has two resistance coils $A$ and $B$,each of $30 \, \Omega$,which may be used separately,in series,or in parallel. Find the value of the current required in each of the three cases.

Find out the following in the electric circuit given in the figure:
$(a)$ Effective resistance of two $8\, \Omega$ resistors in the combination.
$(b)$ Current flowing through $4\, \Omega$ resistor.
$(c)$ Potential difference across $4\, \Omega$ resistor.
$(d)$ Power dissipated in $4\, \Omega$ resistor.
$(e)$ Difference in ammeter readings,if any.

Five bulbs are connected in a series circuit. If the third bulb in the middle blows out,what happens?