A potentiometer wire has a length 4 m and resistance 8 Ω. The resistance that must be connected in series with the wire and an energy source of emf 2 V, so as to get a potential gradient 1 mV per cm of the wire is:
1. 32 Ω
2. 40 Ω
3. 44 Ω
4. 48 Ω
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:
1. | \(1.5\) A | 2. | \(3.0\) A |
3. | \(15\) A | 4. | \(30\) A |
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. \(-3~\text{A}\)
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:
1. | \(4~\Omega\) | 2. | \(2~\Omega\) |
3. | \(3~\Omega\) | 4. | EMF of a cell is required to find the value of \(X\) |
The equivalent resistance between points \(A\) and \(B\) in the circuit shown in the figure is:
1. | \(6R\) | 2. | \(4R\) |
3. | \(2R\) | 4. | \(R\) |
In the circuit shown in the figure below, the current supplied by the battery is:
1. \(2\) A
2. \(1\) A
3. \(0.5\) A
4. \(0.4\) A
1. | \(2~\Omega\) | 2 | \(1~\Omega\) |
3. | \(0.5~\Omega\) | 4. | zero |
When the key K is pressed at time t = 0, which of the following statement about the current I in the resistor AB of the given circuit is true?
1. | I = 2 mA at all t |
2. | I oscillates between 1 mA and 2 mA |
3. | I = 1 mA at all t |
4. | At t = 0 , I = 2 mA and with time, it goes to 1 mA |
In the figure below, what is the potential difference between the point A and B and between B and C, respectively, in steady state?
1.
2.
3.
4.
Power consumed in the given circuit is \(P_1\). On interchanging the position of \(3~\Omega\) and \(12~\Omega\) resistances, the new power consumption is \(P_2\). The ratio of \(\frac{P_2}{P_1}\) is:
1. | \(2\) | 2. | \(1 \over 2\) |
3. | \(3 \over 5\) | 4. | \(2 \over 5\) |