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MCQOPTIONS
This section includes 12583 Mcqs, each offering curated multiple-choice questions to sharpen your Joint Entrance Exam - Main (JEE Main) knowledge and support exam preparation. Choose a topic below to get started.
| 2851. |
In a photoelectric experiment, anode potential is plotted against plate current in figure. Then |
| A. | A and B will have different intensities while B and C will have different frequencies |
| B. | B and C will have different intensities while A and C will have different frequencies |
| C. | A and B will have equal intensities while A and C will have equal frequencies |
| D. | B and C have equal intensities while A and B will have same frequencies |
| Answer» E. | |
| 2852. |
Electrons with de-Broglie wavelength X fall on the target in an X-ray tube. The cut-off wavelength of the emitted X-rays is |
| A. | \[{{\lambda }_{0}}=\frac{2mc{{\lambda }^{2}}}{h}\] |
| B. | \[{{\lambda }_{0}}=\frac{2h}{mc}\] |
| C. | \[{{\lambda }_{0}}=\frac{2{{m}^{2}}{{c}^{2}}{{\lambda }^{3}}}{h}\] |
| D. | \[{{\lambda }_{0}}=\lambda \] |
| Answer» B. \[{{\lambda }_{0}}=\frac{2h}{mc}\] | |
| 2853. |
If the momentum of electron is changed by P, then the de Broglie wavelength associated with it changes by 0.5%. The initial momentum of electron will be: |
| A. | 200P |
| B. | 400P |
| C. | \[\frac{P}{200}\] |
| D. | 100P |
| Answer» B. 400P | |
| 2854. |
A potentiometer arrangement is shown in fig. The driver cell has emf e and internal resistance r. The resistance of potentiometer wire AB is R. F is the cell of em e/3 and internal resistance r/3. Balance point (J) can be obtained for all finite values of |
| A. | R>r/2 |
| B. | R<r/2 |
| C. | R>r/3 |
| D. | R<r/3 |
| Answer» B. R<r/2 | |
| 2855. |
The incorrect option in the given circuit if the reading of ammeter is zero is |
| A. | The value of \[{{\varepsilon }_{1}}\]will be \[\frac{\varepsilon \left( R+r \right)}{R}\] |
| B. | Current in R is \[\frac{\varepsilon {{ }_{1}}}{r+R}\] |
| C. | Value of \[\varepsilon {{ }_{1}}\], will be\[\varepsilon \] |
| D. | Potential across 2R is zero. |
| Answer» D. Potential across 2R is zero. | |
| 2856. |
In an experiment of potentiometer for measuring the internal resistance of primary cell a balancing length \[\ell \] is obtained on the potentiometer wire when the cell is open circuit. Now the cell is short circuited by a resistance R. If R is to be equal to the internal resistance of the cell the balancing length on the potentiometer wire will be |
| A. | \[\ell \] |
| B. | 2 \[\ell \] |
| C. | \[\ell \] /2 |
| D. | \[\ell \] /4 |
| Answer» D. \[\ell \] /4 | |
| 2857. |
In a meter bridge, the balancing length from the left end (standard resistance of one ohm is in the right gap) is found to be 20 cm. The value of the unknown resistance is |
| A. | \[0.8\Omega \] |
| B. | \[0.5\Omega \] |
| C. | \[0.4\Omega \] |
| D. | \[0.25\Omega \] |
| Answer» E. | |
| 2858. |
The resistances in the two arms of the meter bridge are \[5\Omega \] and \[R\Omega \], respectively. When the resistance R is shunted with an equal resistance, the new balance point is at \[1.6{{l}_{1}}.\]The resistance ?R? is: |
| A. | \[10\Omega \] |
| B. | \[15\Omega \] |
| C. | \[20\Omega \] |
| D. | \[25\Omega \] |
| Answer» C. \[20\Omega \] | |
| 2859. |
The resistance of an ammeter is \[13\Omega \]and its scale is graduate for a current upto 100 amps. After an additional shunt has been connected to this ammeter it becomes possible to measure current upto 750 amperes by this meter. The value of shunt-resistance is |
| A. | \[2\Omega \] |
| B. | \[0.2\Omega \] |
| C. | \[2k\Omega \] |
| D. | \[20\Omega \] |
| Answer» B. \[0.2\Omega \] | |
| 2860. |
In a Wheatstone?s bridge, three resistance P, Q and R connected in the three arms and the fourth arm is formed by two resistances \[{{S}_{1}}\] and \[{{S}_{2}}\]connected in parallel. The condition for the bridge to be balanced will be |
| A. | \[\frac{P}{Q}=\frac{2R}{{{S}_{1}}+{{S}_{2}}}\] |
| B. | \[\frac{P}{Q}=\frac{R\left( {{S}_{1}}+{{S}_{2}} \right)}{{{S}_{1}}{{S}_{2}}}\] |
| C. | \[\frac{P}{Q}=\frac{R\left( {{S}_{1}}+{{S}_{2}} \right)}{2{{S}_{1}}{{S}_{2}}}\] |
| D. | \[\frac{P}{Q}=\frac{R}{{{S}_{1}}+{{S}_{2}}}\] |
| Answer» C. \[\frac{P}{Q}=\frac{R\left( {{S}_{1}}+{{S}_{2}} \right)}{2{{S}_{1}}{{S}_{2}}}\] | |
| 2861. |
The resistance of the four arms P, Q, R and S in a Wheatstone?s bridge are 10 ohm, 30 ohm, 30 ohm and 90 ohm, respectively. The e.m.f. and internal resistance of the cell are 7 volt and 5 ohm respectively. If the galvanometer. If the galvanometer resistance is 50 ohm, the current drawn from the cell will be |
| A. | 0.2 A |
| B. | 0.1 A |
| C. | 2.0 A |
| D. | 1.0 A |
| Answer» B. 0.1 A | |
| 2862. |
In a Wheatstone bridge all the four arms have equal resistance R. If the resistance of galvanometer arm is also R, the equivalent resistance of combination is |
| A. | 2R |
| B. | R/4 |
| C. | R/2 |
| D. | R |
| Answer» E. | |
| 2863. |
The charge flowing through a resistance R varies with time t as \[Q=at-b{{t}^{2}}.\] The total heat produced in R by the time current ceases is |
| A. | \[{{a}^{3}}R/6b\] |
| B. | \[{{a}^{3}}R/3b\] |
| C. | \[\frac{{{a}^{3}}R}{2b}\] |
| D. | \[\frac{{{a}^{3}}R}{b}\] |
| Answer» B. \[{{a}^{3}}R/3b\] | |
| 2864. |
For maximum power from battery the internal resistance of battery r is |
| A. | \[10R\] |
| B. | \[\frac{4R}{9}\] |
| C. | \[\frac{R}{8}\] |
| D. | \[\frac{10R}{9}\] |
| Answer» C. \[\frac{R}{8}\] | |
| 2865. |
It takes 12 minutes to boil 1 liter of water in an electric kettle. Due to some defect it becomes necessary to remove 20% turns of heating coil of the kettle. After repair, how much time will it take to boil 1 liter of water? |
| A. | 9.6 minute |
| B. | 14.4 minute |
| C. | 16.8 minute |
| D. | 18.2 minute |
| Answer» B. 14.4 minute | |
| 2866. |
A battery of e.m.f. 10 V and internal resistance \[0.5\Omega \]is connected across a variable resistance R. The value of R for which the power delivered in it is maximum is given by |
| A. | \[0.5\Omega \] |
| B. | \[1.0\Omega \] |
| C. | \[2.0\Omega \] |
| D. | \[0.25\Omega \] |
| Answer» B. \[1.0\Omega \] | |
| 2867. |
Water boils in the electric kettle in 15 minutes after switching on. If the length of heating wire is decreased to 2/3 of its initial value, then the same amount of water will boil with the same supply voltage in |
| A. | 8 minutes |
| B. | 10 minutes |
| C. | 12 minutes |
| D. | 15 minutes |
| Answer» C. 12 minutes | |
| 2868. |
An electric fan and a heater are marked as 100 W, 220 V and 1000 W, 220 V respectively. The resistance of heater is |
| A. | equal to that of fan |
| B. | lesser than that of fan |
| C. | greater than that of fan |
| D. | zero |
| Answer» C. greater than that of fan | |
| 2869. |
A electric tea kettle has two heating coils. When first coil of resistance \[{{R}_{1}}\]is switched on, the kettle begins to boil tea in 6 minutes. When second coil of resistance \[{{R}_{2}}\]is switched on, the boiling begins in 8 minutes. The value of \[{{R}_{1}}/{{R}_{2}}\]is |
| A. | \[\frac{7}{3}\] |
| B. | \[\frac{3}{7}\] |
| C. | \[\frac{3}{4}\] |
| D. | \[\frac{4}{3}\] |
| Answer» D. \[\frac{4}{3}\] | |
| 2870. |
A current of 3 amp flows through the \[2\Omega \] resistor shown in the circuit. The power dissipated in the \[5-\Omega \]resistor is: |
| A. | 4 watt |
| B. | 2 watt |
| C. | 1 watt |
| D. | 5 watt |
| Answer» E. | |
| 2871. |
In the circuit shown in the figure, if potential at point A is taken to be zero, the potential at point B is |
| A. | -1V |
| B. | +2V |
| C. | -2V |
| D. | +1V |
| Answer» E. | |
| 2872. |
In the circuit shown, current (in A) through 50 V and 30 V batteries are, respectively. |
| A. | 2.5 and 3 |
| B. | 3.5 and 2 |
| C. | 4.5 and 1 |
| D. | 3 and 2.5 |
| Answer» B. 3.5 and 2 | |
| 2873. |
Find out the value of current through \[2\Omega \]resistance for the given circuit. |
| A. | zero |
| B. | 2A |
| C. | 5A |
| D. | 4A |
| Answer» B. 2A | |
| 2874. |
Two batteries of emf 4 V and 8 V with internal resistance \[1\Omega \] and \[2\Omega \]are connected in a circuit with a resistance of \[9\Omega \] as shown in figure. The current and potential difference between the points P and Q are |
| A. | \[\frac{1}{3}A\]and 3 V |
| B. | \[\frac{1}{6}A\] and 4 V |
| C. | \[\frac{1}{9}A\] and 9 V |
| D. | \[\frac{1}{12}A\] and 12 V |
| Answer» B. \[\frac{1}{6}A\] and 4 V | |
| 2875. |
A 9 V battery with internal resistance of 0.512 is connected across an infinite network as shown in the figure. All ammeters \[{{A}_{1}},{{A}_{2}},{{A}_{3}}\]and voltmeter V are ideal. Choose correct statement. |
| A. | Reading of \[A{{ }_{1}}\] is 2 A |
| B. | Reading of \[A{{ }_{1}}\]is 18 A |
| C. | Reading of V is 9 V |
| D. | Reading of V is 7 V |
| Answer» B. Reading of \[A{{ }_{1}}\]is 18 A | |
| 2876. |
In the network shown, each resistance is equals to R. The equivalent resistance between adjacent corners A and D is |
| A. | \[R\] |
| B. | \[\frac{2}{3}R\] |
| C. | \[\frac{3}{7}R\] |
| D. | \[\frac{8}{15}R\] |
| Answer» E. | |
| 2877. |
A, B and C are voltmeters of resistance R, 1.5R and 3R respectively as shown in the figure. When some potential difference is applied between X and Y, the voltmeter readings are \[{{V}_{A}},{{V}_{B}}\]and \[{{V}_{C}}\]respectively. Then |
| A. | \[{{V}_{A}}\ne {{V}_{B}}={{V}_{C}}\] |
| B. | \[{{V}_{A}}={{V}_{B}}\ne {{V}_{C}}\] |
| C. | \[{{V}_{A}}\ne {{V}_{B}}\ne {{V}_{C}}\] |
| D. | \[{{V}_{A}}={{V}_{B}}={{V}_{C}}\] |
| Answer» E. | |
| 2878. |
In the circuit shown in Figure the current through |
| A. | the \[3\Omega \]resistor is 0.50 A. |
| B. | the \[3\Omega \]resistor is 0.25 A. |
| C. | the \[4\Omega \]resistor is 0.50 A. |
| D. | the \[4\Omega \]resistor is 0.25 A. |
| Answer» E. | |
| 2879. |
Three batteries of emf 1V and internal resistance \[1\Omega \]each are connected as shown. Effective emf of combination between the points PQ is |
| A. | zero |
| B. | 1V |
| C. | 2V |
| D. | (2/3)V |
| Answer» B. 1V | |
| 2880. |
Five cells each of emf E and internal resistance r send the same amount of current through an external resistance R whether the cells are connected in parallel or in series. Then the ratio \[\left( \frac{R}{r} \right)\] is |
| A. | \[2\] |
| B. | \[\frac{1}{2}\] |
| C. | \[\frac{1}{5}\] |
| D. | \[1\] |
| Answer» E. | |
| 2881. |
The four wires from a larger circuit intersect at junction A as shown. What is the magnitude and direction of the current between points A and B? |
| A. | 2A from A to B |
| B. | 2A from B to A |
| C. | 3A from A to B |
| D. | 2A from B to A |
| Answer» D. 2A from B to A | |
| 2882. |
A 3 volt battery with negligible internal resistance is connected in a circuit as shown in the figure. |
| A. | 0.0416666666666667 |
| B. | 1.5 A |
| C. | 0.0833333333333333 |
| D. | 1/3 A |
| Answer» C. 0.0833333333333333 | |
| 2883. |
Two sources of equal emf are connected to an external resistance R. The identical resistance of the two sources are \[{{R}_{1}}\] and \[{{R}_{2}}\]\[\left( {{R}_{2}}>{{R}_{1}} \right)\]. If the potential difference across the source having internal resistance \[{{R}_{2}}\]is zero, then |
| A. | \[R={{R}_{2}}-{{R}_{1}}\] |
| B. | \[R={{R}_{2}}\times \left( {{R}_{1}}+{{R}_{2}} \right)/\left( {{R}_{2}}-{{R}_{1}} \right)\] |
| C. | \[R={{R}_{1}}{{R}_{2}}/\left( {{R}_{2}}-{{R}_{1}} \right)\] |
| D. | \[R={{R}_{1}}{{R}_{2}}/\left( {{R}_{1}}-{{R}_{2}} \right)\] |
| Answer» D. \[R={{R}_{1}}{{R}_{2}}/\left( {{R}_{1}}-{{R}_{2}} \right)\] | |
| 2884. |
In the series combination of« cells each cell having emfs and internal resistance r. It three cells are wrongly connected, then total emf and internal resistance of this combination will be |
| A. | \[n\varepsilon ,\left( nr-3r \right)\] |
| B. | \[\left( n\varepsilon -2\varepsilon \right)nr\] |
| C. | \[\left( n\varepsilon -4\varepsilon \right)nr\] |
| D. | \[\left( n\varepsilon -6\varepsilon \right)nr\] |
| Answer» E. | |
| 2885. |
Two wires of the same metal have same length, but their cross-sections are in the ratio 3 : 1. They are joined in series. The resistance of thicker wire is \[10\Omega .\]The total resistance of the combination will be |
| A. | \[10\Omega \] |
| B. | \[20\Omega \] |
| C. | \[40\Omega \] |
| D. | \[100\Omega \] |
| Answer» D. \[100\Omega \] | |
| 2886. |
The effective resistance between the terminals |
| A. | \[5\Omega \] |
| B. | \[10\Omega \] |
| C. | \[15\Omega \] |
| D. | \[20\Omega \] |
| Answer» B. \[10\Omega \] | |
| 2887. |
Find equivalent resistance between A&B in the following circuit |
| A. | \[\frac{3R}{2}\] |
| B. | \[\frac{2R}{3}\] |
| C. | \[2R\] |
| D. | \[3R\] |
| Answer» C. \[2R\] | |
| 2888. |
All wires have same resistance and equivalent resistance between A and B is Ry. Now keys are closed, then the equivalent resistance will become |
| A. | \[\frac{7{{R}_{0}}}{3}\] |
| B. | \[\frac{7{{R}_{0}}}{9}\] |
| C. | \[7{{R}_{0}}\] |
| D. | \[\frac{{{R}_{0}}}{3}\] |
| Answer» C. \[7{{R}_{0}}\] | |
| 2889. |
In the given network of four resistances, the equivalent resistance is: |
| A. | \[20\Omega \] |
| B. | \[5.4\Omega \] |
| C. | \[12\Omega \] |
| D. | \[4.5\Omega \] |
| Answer» E. | |
| 2890. |
A primary cell has an e.m.f. of 1.5 volt. When short-circuited it gives a current of 3 ampere. The internal resistance of the cell is |
| A. | 4.5 ohm |
| B. | 2 ohm |
| C. | 0.5 ohm |
| D. | (1/4.5) ohm |
| Answer» D. (1/4.5) ohm | |
| 2891. |
The internal resistance of a 2.1 V cell which gives a current of 0.2 A through a resistance of \[10\Omega \]is |
| A. | \[0.5\Omega \] |
| B. | \[0.8\Omega \] |
| C. | \[1.0\Omega \] |
| D. | \[0.2\Omega \] |
| Answer» B. \[0.8\Omega \] | |
| 2892. |
If n cells each of emf \[\varepsilon \]and internal resistance r are connected in parallel, then the total emf and internal resistances will be |
| A. | \[\varepsilon ,\frac{r}{n}\] |
| B. | \[\varepsilon ,nr\] |
| C. | \[n\varepsilon ,\frac{r}{n}\] |
| D. | \[n\varepsilon ,rn\] |
| Answer» B. \[\varepsilon ,nr\] | |
| 2893. |
In a certain paricle accelerator, electrons emerge in pulses at the rate of 250 pulses per second. Each pulse is of duration of 200ns and the electrons in the pulse constitute a current of 250mA. The number of electrons delivered by the accelerator per pulse is |
| A. | \[8.00\times {{10}^{10}}\] |
| B. | \[5.00\times {{10}^{10}}\] |
| C. | \[3.13\times {{10}^{11}}\] |
| D. | \[9.60\times {{10}^{10}}\] |
| Answer» D. \[9.60\times {{10}^{10}}\] | |
| 2894. |
A cell of internal resistance r is connected to an external resistance R. The current will be maximum in R, if |
| A. | \[R=r\] |
| B. | \[R<r\] |
| C. | \[R>r\] |
| D. | \[\,R=r/2\] |
| Answer» B. \[R<r\] | |
| 2895. |
The Kirchhoff?s second law \[\left( \Sigma R\text{ }=\text{ }\Sigma E \right),\]where the symbols have their usual meanings, is based on |
| A. | conservation of momemtum |
| B. | conservation of charge |
| C. | conservation of potential |
| D. | conservation of energy |
| Answer» E. | |
| 2896. |
What will be the change in the resistance of a circuit consisting of five identical conductors if two similar conductors are added as shown by the dashed line in figure. |
| A. | becomes 1/5 times |
| B. | becomes 3/5 times |
| C. | becomes 2/5 times |
| D. | becomes 1/2 times |
| Answer» C. becomes 2/5 times | |
| 2897. |
A 12 cm wire is given a shape of a right angled triangle ABC having sides 3 cm, 4 cm and 5 cm as shown in the figure. The resistance between two ends (AB, BC, CA) of the respective sides are measured one by one a multi-meter. The resistances will be in the ratio of |
| A. | 0.127835648148148 |
| B. | 0.386400462962963 |
| C. | 1.14762731481481 |
| D. | 0.891956018518519 |
| Answer» D. 0.891956018518519 | |
| 2898. |
A hank of uninsulated wire consisting of seven and a half turns is stretched between two nails hammered into a board to which the ends of the wire are fixed. The resistance of the circuit between the nails is determined with the help of electrical measuring instruments. Determine the proportion in which the resistance will change if the wire is unwound so that the ends remain to be fixed to the nails. |
| A. | 225 |
| B. | 15 |
| C. | 240 |
| D. | 250 |
| Answer» B. 15 | |
| 2899. |
Find the equivalent resistance between A and B (resistance of each resistor is R.) |
| A. | \[\frac{7}{12}R\] |
| B. | \[\frac{7}{13}R\] |
| C. | \[\frac{7}{15}R\] |
| D. | \[\frac{8}{13}R\] |
| Answer» B. \[\frac{7}{13}R\] | |
| 2900. |
Each of the resistors shown in Fig. has resistance R. Find the equivalent resistance between A and B. |
| A. | \[\frac{7R}{4}\] |
| B. | \[\frac{5R}{4}\] |
| C. | \[\frac{9R}{4}\] |
| D. | \[\frac{11R}{4}\] |
| Answer» E. | |