Three resistors are connected to a \(20\) V battery with a constant voltage supply. One of the resistors is a variable resistor. The resistance of the variable resistor is gradually increased from \(0~\Omega\) to \(5\) \(\Omega.\)
   

Which graph correctly represents how the current drawn from the battery varies with the resistance \((R)\) of the variable resistor?

1.		2.
3.		4.

In the circuit shown in the figure below, the current supplied by the battery is:
 
1. \(2~\text A\) 
2. \(1~\text A\) 
3. \(0.5~\text A\) 
4. \(0.4~\text A\) 

The equivalent resistance between points \(A\) and \(B\) in the circuit shown in the figure is:

In the circuit shown in the figure below, if the potential difference between \(B\) and \(D\) is zero, then value of the unknown resistance \(X\) is:

The figure below shows a network of currents. The current \(i\) will be:

           

1. \(3~\text{A}\)
2. \(13~\text{A}\)
3. \(23~\text{A}\)
4. \(-3~\text{A}\)

Eels are able to generate current with biological cells called electroplaques. The electroplaques in an eel are arranged in \(100\) rows, each row stretching horizontally along the body of the fish containing \(5000\) electroplaques. The arrangement is suggestively shown below. Each electroplaques has an emf of \(0.15\) V and internal resistance of \(0.25~\Omega\).

The water surrounding the eel completes a circuit between the head and its tail. If the water surrounding it has a resistance of \(500~\Omega\), the current an eel can produce in water is about:

A student has three \(6.0~\Omega\) resistors that can be connected together in any configuration. What are the maximum and minimum resistances that can be obtained by using one or more of these three resistors?
(Assume the connections between the resistors have negligible resistance, the temperature of the resistors is constant, and the resistors are used in a d.c. circuit and none of the resistors are short-circuited.)

Figure \((a)\) below shows a Wheatstone bridge in which \(P,Q,R,S\) are fixed resistances, \(G\) is a galvanometer, and \(B\) is a battery. For this particular case, the galvanometer shows zero deflection. Now, only the positions of \(B\) and \(G\) are interchanged, as shown in the figure \((b).\) The new deflection of the galvanometer:
                  
1. is to the left
2. is to the right
3. is zero
4. depends on the values of \(P,Q,R,S\)