Two wires of resistance R1 and R2 have temperature coefficient of resistance , respectively. These are joined in series. The effective temperature coefficient of resistance is :

(1) $\frac{{\alpha }_{1}+{\alpha }_{2}}{2}$

(2) $\sqrt{{\alpha }_{1}{\alpha }_{2}}$

(3) $\frac{{\alpha }_{1}{R}_{1}+{\alpha }_{2}{R}_{2}}{{R}_{1}+{R}_{2}}$

(4) $\frac{\sqrt{{R}_{1}{R}_{2}{\alpha }_{1}{\alpha }_{2}}}{\sqrt{{R}_{1}^{2}+{R}_{2}^{2}}}$

Concept Questions :-

Combination of resistors
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

Two cells of equal e.m.f. and of internal resistances, r1, and ${r}_{2}\left({r}_{1}>{r}_{2}\right)$ are connected in series. On connecting this combination to an external resistance R, it is observed that the potential difference across the first cell becomes zero. The value of R will be :

(1) ${r}_{1}+{r}_{2}$

(2) ${r}_{1}-{r}_{2}$

(3) $\frac{{r}_{1}+{r}_{2}}{2}$

(4) $\frac{{r}_{1}-{r}_{2}}{2}$

Concept Questions :-

Grouping of cells
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

When connected across the terminals of a cell, a voltmeter measures 5V and a connected ammeter measures 10 A of current. A resistance of 2 ohms is connected across the terminals of the cell. The current flowing through this resistance will be :

(1) 2.5 A

(2) 2.0 A

(3) 5.0 A

(4) 7.5 A

Concept Questions :-

Kirchoff's voltage law
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

In the circuit shown here, E1 = E2 = E3 = 2 V and R1 = R2 = 4 ohms. The current flowing between points A and B through battery E2 is

(1) Zero

(2) 2 amp from A to B

(3) 2 amp from B to A

(4) None of the above

Concept Questions :-

Grouping of cells
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

In the circuit shown below E1 = 4.0 V, R1= 2 Ω, E2 = 6.0 V, R2 = 4 Ω and R3 = 2 Ω. The current I1 is :

(1) 1.6 A

(2) 1.8 A

(3) 1.25 A

(4) 1.0 A

Concept Questions :-

Grouping of cells
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

The potential difference across 8 ohms resistance is 48 volts as shown in the figure. The value of potential difference across X and Y points will be :

(1) 160 volt

(2) 128 volt

(3) 80 volt

(4) 62 volt

Concept Questions :-

Combination of resistors
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

Two resistances R1 and R2 are made of different materials. The temperature coefficient of the material of R1 is α and of the material of R2 is –β. The resistance of the series combination of R1 and R2 will not change with temperature, if R1/ R2 equals :

(1) $\frac{\alpha }{\beta }$

(2) $\frac{\alpha +\beta }{\alpha -\beta }$

(3) $\frac{{\alpha }^{2}+{\beta }^{2}}{\alpha \beta }$

(4) $\frac{\beta }{\alpha }$

Concept Questions :-

Derivation of Ohm's law
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

An ionization chamber with parallel conducting plates as anode and cathode has $5×{10}^{7}$ electrons and the same number of singly-charged positive ions per cm3. The electrons are moving at 0.4 m/s. The current density from anode to cathode is $4\text{\hspace{0.17em}}\mu A/{m}^{2}$. The velocity of positive ions moving towards cathode is :

(1) 0.4 m/s

(2) 16 m/s

(3) Zero

(4) 0.1 m/s

Concept Questions :-

Current and current density
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A wire of resistance 10 Ω is bent to form a circle. P and Q are points on the circumference of the circle dividing it into a quadrant and are connected to a Battery of 3 V and internal resistance 1 Ω as shown in the figure. The currents in the two parts of the circle are

(1)

(2) $\frac{5}{26}A\text{\hspace{0.17em}\hspace{0.17em}and\hspace{0.17em}}\frac{15}{26}A$

(3)

(4)

Concept Questions :-

Kirchoff's voltage law
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

In the given circuit, it is observed that the current I is independent of the value of the resistance R6. Then the resistance values must satisfy

(1) ${R}_{1}{R}_{2}{R}_{5}={R}_{3}{R}_{4}{R}_{6}$

(2) $\frac{1}{{R}_{5}}+\frac{1}{{R}_{6}}=\frac{1}{{R}_{1}+{R}_{2}}+\frac{1}{{R}_{3}+{R}_{4}}$

(3) ${R}_{1}{R}_{4}={R}_{2}{R}_{3}$

(4) ${R}_{1}{R}_{3}={R}_{2}{R}_{4}={R}_{5}{R}_{6}$

Concept Questions :-

Combination of resistors