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The circuit shows a lamp of rating '$6$ V, $9$ W' connected in series with a resistor $R$ and a $9$ V battery. What should be the resistance of $R$ if the lamp is to work as rated ?

An electric heater of rating "$2000$ W, $200$ V" and an electric cooker of rating "$500$ W, $200$ V" are connected in parallel to a $200$ V a.c. source. The total power of the two appliances is

$P$ and $Q$ are bulbs of rating "$40$ W, $200$ V" while $R$ and $S$ are of rating "$60$ W, $200$ V". Which of the following circuits gives the maximum brightness ? (Assume all circuits are connected to the same voltage.)

Electric bulbs $R$ of rating "$40$ W, $200$ V" and electric bulbs $S$ of rating "$60$ W, $200$ V". Which of the following combinations would produce the maximum brightness if connected to the same voltage ?

Two heaters of rating '$1$ kW, $200$ V' and '$2$ kW, $200$ V' respectively are connected in series to a $200$ V supply. What is the total power consumed by the heaters ?

Which of the following has the greatest current when it is operated at $200$ V ?

In the figure shown, $S$ is a switch to turn on and off the electric fan. $X$, $Y$ and $Z$ are wires to be connected to the three terminals of a plug. How should $X$, $Y$ and $Z$ be connected to the three pins (E, L and N) of a given plug ?

Eight $100$ W lamps and one $1000$ W heater are all connected in parallel to a mains supply of $200$ V. Which of the following should be used ?

The table below shows the voltage and power rating for various electrical appliances. Which of the electric appliances has the smallest working resistance ?

A set of Christmas tree lights consists of $20$ bulbs in series. Each bulb has a rating of "$10$ V $5$ W". One of the bulbs burns out and Jimmy goes to buy a replacement. When he gets back, he finds that although the new bulb is marked $5$ W, it looks dimmer than the others when the lights are turned on. The most probable reason for this is that the new bulb