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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 301. |
Fill in the blanks:a. A device that is used to break an electric circuit is called.......b. An electric cell has .............. |
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Answer» a. A device that is used to break an electric circuit is called Switch. b. An electric cell has Two. |
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| 302. |
Fill in the blanks:(a) A device that is used to break an electric circuit is called _______.(b) An electric cell has _______ terminals. |
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Answer» (a) switch (b) two |
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| 303. |
How many types of electric circuit are there ?(i) Open electric circuits (ii) Closed electric circuits |
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Answer» (i) Open electric circuits: The circuit in which electrical contact at any point is broken is called Open circuits (ii) Closed electric circuits: The circuit in which electrical current flows from one terminal of a cell or battery to the other is called closed circuits. |
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| 304. |
Two particles X and Y, of equal mass and with unequal positive charges, are free to move and are initially far away from each other. With Y at rest, X begins to move towards it with initial velocity u. After a long time, finally (a) X will stop, Y will move with velocity u (b) X and Y will both move with velocities u/2 each (c) X will stop, Y will move with velocity < u (d) both will move with velocities < u/2 |
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Answer» Correct Answer is: (a) X will stop, Y will move with velocity u This is similar to one-dimensional, elastic collisions between bodies of equal masses, and results in exchange of velocities. |
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| 305. |
If the earth’s surface is treated as a conducting surface with some charge, what should be the order of magnitude of the charge per unit area, in C/m2, so that a proton remains suspended in space near the earth’s surface? (a) 10-18 (b) 10-12 (c) 10-6 (d) 1 |
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Answer» Correct Answer is: (a) 10-18 Let σ = charge per unit area on the earth’s surface. Then, the field near the surface = E = σ/ε0. The upward force on a proton = eE = eσ/ε0. The downward force = mg.. For equilibrium, mg = eσ/ε0 or σ = ε0mg/ε0. σ = 8.85 x 10-12 x 1.67 x 10-27 x 10 / 1.6 x 10-19 C/m2 ~ 10-18 C/m2. |
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| 306. |
In a certain charge distribution, all points having zero potential can be joined by a circle S. Points inside S have positive potential, and points outside S have negative potential. A positive charge, which is free to move, is placed inside S. (a) It will remain in equilibrium. (b) It can move inside S, but it cannot cross S. (c) It must cross S at some time. (d) It may move, but will ultimately return to its starting point. |
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Answer» Correct Answer is (c) It must cross S at some time. |
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| 307. |
A spherical equipotential surface is not possible (a) for a point charge (b) for a dipole (c) inside a uniformly charged sphere (d) inside a spherical capacitor |
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Answer» Correct Answer is: (b) for a dipole |
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| 308. |
In a uniform electric field, equipotential surfaces must (a) be plane surfaces (b) be normal to the direction of the field (c) be spaced such that surfaces having equal differences in potential are separated by equal distances (d) have decreasing potentials in the direction of the field |
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Answer» Correct Answer is: (a, b, c, & d) |
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| 309. |
A solid metallic sphere is placed in a uniform electric field. Which of the curves shown in the figure represent the lines of force correctly? |
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Answer» Correct Answer is: (d) The field is zero inside a conductor and hence lines of force cannot exist inside it. Also, due to induced charges on its surface, the field is distorted close to its surface, and a line of force must deviate near the surface outside the sphere. |
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| 310. |
Charge Q is given a displacement Vector r = ai + bj in an electric field Vector E = E1i + E2j . The work done is (a) Q(E1a + E2b)(b) Q√((E1a)2 + (E2b)2)(c) Q(E1 + E2) √(a2 + b2)(d) Q√((E12 + E22)) √(a2 + b2) |
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Answer» Correct Answer is: (a) Q(E1a + E2b) The force is Vector F = Q Vector E. The work is W = Vector F. Vector r = Q(Vector E . Vector r) |
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| 311. |
The porous pot in Leclanche cell contains `"_____"` with a carbon rod dipped in it. |
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Answer» Correct Answer - C The porous pot in Leclanche cell contains powdered carbon and manganese dioxide with a carbon rod ripped in it. |
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| 312. |
Which of the following is a bad conductor of electricity ?A. GoldB. CopperC. Pure alcoholD. Living plant |
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Answer» Correct Answer - C Among the given options impure water is the better con-ductor of electricity. |
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| 313. |
For how many hours can a 100 W bulb be sued to have one unit of electrical energy consumption ? |
| Answer» When used for identical time, a 100 W bulb consumers only `1/(10^(th))` of the energy consumd by a 1000 W bulb. For equal consumption of electrical energy, a 100 W is used for a time that is 10 times the time a 1000 W bulb is used. If a 1000 W bulb consumes one unit of electrical energy when used for one hour, then a 100 W bulb consumes the same one unit of electrical energy if it is used for 10 hours. | |
| 314. |
Name two effects produced by electric current |
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Answer» Two effects of produced by electric current are: (a) Heating effect (b) Magnectic effect |
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| 315. |
Indentify the correct statement/s related to local action in a voltaic cell. (a) Carbon and iron particles present in zinc plate act as impurities.(b) Impurities react with acid and with the zinc par-ticles to form a large number of tiny cells creat-ing local electric circuits.A. Only (A) is true.B. Only (B) is true.C. Both (A) and (B) true.D. Both (A) and (B) false. |
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Answer» Correct Answer - C Carbon and iron particles present in zinc plate act as impurities and these particles react with acid and with the zinc particles to form a large number of tiny cells. The results in local action in a voltaic cell. |
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| 316. |
Explain the following : a) Heating effects of electric current. b) Magnetic effects of electric current. |
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Answer» a) Heating effects of electric current: 1. The production of heart due to the flow of electricity through a wire is called heating effects of electricity. 2. Electric devices like electric stoves, room heaters, iron boxes, electric kettles, electric cookers, heaters, geysers, hair dryers work on the principle of heating effects of electric current. 3. All these appliances contain a heating element is called a filament. 4. Generally, a filament is made up of Nichrome in iron boxes and the filaments of an electric bulb is made of Tungsten. b) Magnetic effects of electric current: 1. The production of magnetic force due to the flow of electricity through a wire is called magnetic effect of electricity. 2. The devices which act as magnets when electricity passes through them are called electromagnets. 3. The electric devices like loudspeakers, fan, bell, motor, mixer grinders, MRI machines, generators, metal detectors, mobile phones work on the principle of magnetic effect of electricity. 4. Magnetic effects produced in a coil which is wound around a soft iron due to the passing of electricity in the coil. |
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| 317. |
Four cells, each of e.m.f 1.5 V, are connected in series to form a battery. Find the e.m.f of the bettery. |
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Answer» When the four cells are connected in series, the e.m.f. of the bettery `E = E_(1) + E_(2) + E_(3) + E_(4) = 1.5+1.5+1.5+1.5=6 V`. |
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| 318. |
Name the way of charging a conductor in which the charge is shared. |
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Answer» By conduction is the way of charging a conductor in the charge is shared. |
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| 319. |
A metal rod A is to be charged positively by using another charged rod B. What should be the kind of charge on the rod B if charging is to be done by conduction ? |
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Answer» Road A is uncharged and Rod B is charged body. A is to be charged positively by touching i.e. by conduction. So rod / B should have the similar charge as is required by A i. e. +vely. So rod B should be positively charged, ∴ By conduction same kind of charge is produced and shared by uncharged body. |
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| 320. |
Write the following steps in sequence that explains the charging of a body by conduction. (A) Bring this positively charged glass rod in contact with a (neutral) uncharged metallic body, because of this the metallic body also becomes positively charged. (B) Take a glass rod and rub it with silk cloth. (C) Some electrons move from the glass rod to the silk cloth because of this the glass and becomes positively charged.A. ABCB. BCAC. ACBD. BAC |
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Answer» Correct Answer - B First take a glass rod and rub it with silk cloth. Because of this, some electrons move from the glass rod to the silk cloth and glass rod becomes positively charged. Now, bring this positively charged glass rod in contact with a uncharged metallic body because of this metallic body also acquires positive charges. |
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| 321. |
A gold leaf electroscope is to be charged positively by conduction. For this1. a positively charged rod is held close to near the disc of electroscope2. a positively charged rod is placed in contact with the disc of electroscope3. a negatively charged rod is held near the disc of electroscope4. a negatively charged rod is touched with the disc of electroscope |
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Answer» a positively charged rod is placed in contact with the disc of electroscope |
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| 322. |
If a glass rod is positively charged, then it consists of particles withA. only positive charge.B. only negative charge.C. both negative and positive charges, but the num-ber of positively charged particles are more than the number of negatively charged particles.D. both negative and positive charged bu the num-ber of negatively charged particles are more than the number of positively charged particles. |
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Answer» Correct Answer - A::C::D All bodies are made up of negatively charged and positively |
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| 323. |
A negatively charged ebonite rod is touched with the disc of a negatively charged gold leaf electroscope. What will be your observation ? |
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Answer» Divergence of leaves will increase because the similar charge will increase. |
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| 324. |
Describe Franklin’s experiment. What did he conclude from his experiment ? |
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Answer» FRANKLIN’S EXPERIMENT: Franklin flew a kite made of silk in a thunder-storm. At the top comer of the kite, he fixed a metal wire about 30 cm long. The other end of the wire was joined to the string. At the lower end of the string, he tied a metal key. When the string got wet, he obtained a number of sparks between his Knuckle and the key. He concluded from his experiment that in a thunderstorm, the clouds acquire an electric charge due to friction. |
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| 325. |
Choose the correct statement(s) in case of a voltric cell. (A) Cathode used is Zn and anode used is copper. (B) The electrolyte used is dilute sulphuric acid.A. Only A is trueB. Only B is trueC. Both A and B are trueD. Both A and B are false |
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Answer» Correct Answer - C In voltaic cell zinc is the negative electrode , i.e, cath-ode and copper is the positive electrode, i.e., anode. The electrolyte used is dilute sulphric acid. |
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| 326. |
Choose the correct statement(s) in case of a voltric cell. (A) Cathode used is Zn and anode used is copper. (B) The electrolyte used is dilute sulphuric acid.A. Only (A) is true.B. Only (B) is true.C. Both (A) and (B) true.D. Both (A) and (B) are false. |
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Answer» Correct Answer - C In voltaic cell zinc is the negative electrode , i.e, cath-ode and copper is the positive electrode, i.e., anode. The electrolyte used is dilute sulphric acid. |
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| 327. |
The lemon juice in a cell is acts as a A) Anode B) Cathode C) Electrolyte D) None |
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Answer» The correct option is C) Electrolyte. |
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| 328. |
The container of a dry cell works as A) Anode B) Cathode C) Electrolyte D) None |
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Answer» The correct option is B) Cathode. |
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| 329. |
Generally the chemical used in a dry cell is A) Copper sulphate B) Sodium chloride C) Ammonium chlorideD) Potassium hydride |
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Answer» The correct option is C) Ammonium chloride. |
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| 330. |
A carbon rod with a metal cap in a cell works as A) Anode B) Cathode C) Electrolyte D) None |
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Answer» The correct option is A) Anode. |
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| 331. |
The positive electrode in a cell is called A) Electrolyte B) Anode C) Cathode D) Filament |
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Answer» The correct option is B) Anode. |
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| 332. |
A and B are two identical conducting rods. A is given positive charge and B is connected to a cell as shown in the figure. Will there be any change in the electrostatic force between A and B if the switch is closed ? |
| Answer» There will be no electrostatic force between A and B. When switch is closed, electric current passes through B. The quantity of charge entering B is equal to the quanity of charge leaving B making it electrically neutral . And as charges in B are in motion, attraction between A and B of electrostatic induction is negligible. | |
| 333. |
With the help of an electroscope, how can we iden-tify the presence and nature of charge on a body? |
| Answer» If metal strips in the jar deviate when a body is brought in contact with the metallic disc, then the body is charged. To know the nature of charge on the body, first one we must charge the electroscope with known polarity. Then if a body of identica polarity is brought near the metallic disc, we observe increased deviation in metal strips. If it is of opposite polarity, the metal strips collapse or come closer. | |
| 334. |
Explain the following;How does the resistance of a wire vary with its area of cross section ? |
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Answer» Resistance is inversely proportional to the area of the cross-section of the wire. Thus, if the wire is thick, then resistance is less. If the wire is thin, then resistance is large. |
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| 335. |
The potential difference between two points in an electric circuit is 1 volt. What does it mean? Name a device that helps to measure the potential difference across a conductor. |
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Answer» The potential difference between two points is 1 volt means that if a charge of 1 coulomb is moved Ilom one point to the other, 1 joule of work is required. The potential difference across a conductor is measured by means of an instrument called the "voltmeter." |
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| 336. |
Consider the circuits given below :(a) In which circuit are the lamps dimmest ? (b) In which circuit or circuits are the lamps of equal brightness to the lamps in circuit (/) ?(c) Which circuit gives out the maximum light ? |
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Answer» (a) circuit (ii) (b) circuit (iii) (c) circuit (iii) |
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| 337. |
How can you change the brightness of the lamps ? |
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Answer» The brightness of the lamps can be changed by connecting the lamps in parallel. |
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| 338. |
Consider the circuit given below where A, B and C are three identical light bulbs of constant resistance.(a) List the bulbs in order of increasing brightness. (b) If C burns out, what will be the brightness of A now compared with before ?(c) If B burns out instead, what will be the brightness of A and C compared with before ? |
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Answer» (a) C will be the brightest. Voltage will be distributed equally between A and B, so they will have equal brightness but lesser than that of C. (b) A gets the same voltage as before, so its brightness remains the same. (c) If B burns put, A will also stop glowing because it is connected in series with B. However, brightness of C remains the same. |
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| 339. |
If current flows through two lamps arranged : (a) in series, (b) in parallel, and the filament of one lamps breaks, what happens to the other lamp ? Explain your answer. |
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Answer» (a) In case of series connection, if filament of one lamp breaks, the other wil stop glowing. (b) In case of parallel connection, if filament of one lamp breaks, the other will keep glowing. |
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| 340. |
How do you think the brightness of two lamps arranged in parallel compares with the brightness of two lamps arranged in series (both arrangements having one cell) ? |
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Answer» The brightness of two lamps arranged in parallel is much more those arranged in series. |
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| 341. |
State three factors on which the heat produced by an electric current depends. How does it depend on these factors ? |
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Answer» Heat produced by an electric current depends on the following factors: (i) Heat produced is directly proportional to square of current. (ii) Heat produced is directly proportional to resistance. (iii) Heat produced is directly proportional to the time for which current flows. |
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| 342. |
If the current passing through a conductor is doubled, what will be the change in heat produced ? |
| Answer» Heat produced is directly proportional to the square of current. If current I is doubled, heat H will be four times. | |
| 343. |
Name a substance whose resistance decrease with temperature. |
| Answer» Geranium (a semiconductor). | |
| 344. |
An electric lamb of `100 Omega`, a toaster of resistance `50 Omega` and a water filter of resistance `500 Omega` are connected in parallel to a `220 V` source. What is the resistance of an electric iron connected to the same source that takes as much current as all three appliances ans what is the current through it ? |
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Answer» Resistance of the electric lamp, `r_1 = 100 Omega` resistance of toaster, `r_1 = 50 Omega` Resistance of water filter, `r_3 = 500 Omega` Since `r_1,r_2 and r_3` are connected in parallel, their equivalent resistance `(R_p)` is given by `(1)/(R_p) = (1)/(r_1) + (1)/(r_2)+(1)/(r_3) = (1)/(100) + (1)/(50) + (1)/(500) = (5 + 10 + 1)/(500) = (16)/(500)` or `R_p = (500)/(16) Omega = (125)/(4) Omega` Current through the three appliances,i.e., `I = (V)/(R_p) =(220 V)/((125//4)Omega) = 7.04 A` Since the electric iron connected to the same source `(i.e., 220 V)`, takes as much current as taken by all the three appliances,i.e., `I`, its resistance is equal to `R_p`,i.e., `(125//4) Omega = 31.25 Omega` Current through the electric iron, `I = 7.04 A`. |
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| 345. |
Assertion (A) : The electrical appliances connected in series do not work to their full capacity. Reason (R ) : The electrical energy drawn from the battery is shared by all the appliances connected in series.A. Both A and R are true and R is the correct explanation of A.B. Both A and R are true and R is not the correct explanation of A.C. A is true but R is false.D. Both A and R are false. |
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Answer» Correct Answer - A The electrical appliance connected in series do not work to their full capacity because the electrical energy drawn from the battery is shared by all the appliance connected in series. |
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| 346. |
Assertion (A): A 1000 W bulb when used for 1 hour consumes the same number of electrical units as that of 100 W bulb that is used for 10 hours. Reason (R ) : On electrical unit is charged when one kilowatt hour electrical energy is consumed.A. Both A and R are true and R is the correct explanation of A.B. Both A and R are true and R is not the correct explanation of A.C. A is true but R is false.D. Both A and R are false. |
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Answer» Correct Answer - A We know `1` unit `= 1 kWh = 100 kW h = 100 W xx 1 h = 100 W xx 10 h` So, `100W` bulb used for 10 h and 1000 W bulb used for 1 h consumes same amount of electrical energy, i.e, 1 kWh or one electrical unit. |
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| 347. |
What is meant by the “resistance of a conductor” ? Write the relation between resistance, potential difference and current. |
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Answer» Solution : The property of a conductor due to which it opposes the flow of current through it is called resistance of the conductor. Work done = Potential difference x charge moved. |
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| 348. |
Write relation between heat energy produced in a conductor when a potential difference V is applied across its terminals and a current I flows through for ‘t’ |
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Answer» Heat produced, H = VIt |
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| 349. |
The capacity of a sphere, which, when a charge of `0.5 C` is placed on it, raises its potential by 100 volt is `"_________"` farad.A. 50B. 200C. `5xx 10^(-3)`D. `0.5` |
| Answer» Correct Answer - C | |
| 350. |
The device used for producting electric current is called a :A. an ammeter and is always connected parallel to the circuit.B. an ammeter and is always connected in series in the circuitC. a voltmeter and is always connceted parallel to the circuitD. a voltmeter and is always connected in series in the circuit. |
| Answer» Correct Answer - B | |