Multiple Choice Questions (MCQs)

The figure given below shows three resistors:

Their combined resistance is

If two resistors of $25 \mathrm{\Omega }$ and $15 \mathrm{\Omega }$ are joined together in series and then placed in parallel with a $40 \mathrm{\Omega }$ resistor, the effective resistance of the combination is:

The diagram below shows part of a circuit:

If this arrangement of three resistors was to be replaced by a single resistor, its resistance should be:

In the circuit shown below:
                      
The potential difference across the $3 \mathrm{\Omega }$ resistor is:

A battery and three lamps of equal resistance are connected as shown:

Which of the following statements about the current at $X,Y$and $Z$ is correct?

$V_1, V_2, V_3$ are the p.ds. across the $1 \mathrm{\Omega }, 2 \mathrm{\Omega } \mathrm{and} 3 \mathrm{\Omega }$ resistors in the following diagram, and the current is $5 \mathrm{A}$.

Which one of the columns $\left(a\right)$ to $\left(d\right)$ shows the correct values of $V_1, V_2$ and $V_3$ measured in $\mathrm{volts}$?

A wire of resistance $R_1$ is cut into five equal pieces. These five pieces of wire are then connected in parallel. If the resultant resistance of this combination be $R_2$, then the ratio $\frac{R_1}{R_2}$ is: