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Electrical Appliances Free Doubts and Solutions

WHY CURRENT  OF  220V  IS  HARMFUL  ?

Asked by pardeepkumar2281 4th October 2018, 9:41 PM
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Why can we not use rubber to make electric wires?

Asked by kv.cyfuture 3rd September 2018, 12:58 PM
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To increase the range of an ammeter to n times, the value of shunt reuired is ( G = resistance of galvanometer )   1. G / n 2. G / n - 1 3. ( n - 1 ) / G 4. nG

Asked by rajeshtitu 17th July 2016, 8:57 PM
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The potential difference across a resistor 'r' carrying current 'I' IS Ir. ( 1 ) If the potential difference across 'r' is measured using a voltmeter of resistence 'Rv', s how that the reading of voltmeter is less thsn the true value. 2. find the percentage error in measuring the potential differene by a voltmeter 3.At what value of Rv, does the voltmeter measures the true potential difference

Asked by Rajeev 17th February 2016, 10:55 AM
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in que 23 of ncert, why does the current i does not change when resistance is changed from R to X. actully which current is referred to i. thanks

Asked by anmeni11 19th October 2015, 9:31 AM
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The power of the  wre having potential difference 200 V across its end is 100 W.If the wire is cut into two equal parts,then what will be  the energy per sec  consumed by the wire.

Asked by kharendra 10th July 2015, 11:28 PM
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Ajit had a high tension tower erected on his farm land. He kept complaining to the authorities to remove it as it was occupying a large portion of his land. His uncle, who was a teacher, explained to him the need for erecting these towers for efficient transmission of power. As Ajit realised its significance, he stopped complaining. Answer the following questions:                                                                                   (a) Why is it necessary to transport power at high voltage? (b) A low power factor implies large power loss. Explain. (c) Write two values each displayed by Ajit and his uncle

Asked by Topperlearning User 10th July 2015, 8:56 AM
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CBSE - XII Science - Physics - Current Electricity

Asked by Anita Sarraf Sathyavageeswaran 10th June 2015, 6:17 PM
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<div><img class="Wirisformula" src="https://images.topperlearning.com/topper/tinymce/integration/showimage.php?formula=d1deb7b0d67d5cf84a1c7f9706e500c5.png" alt="W i t h space t w o space r e s i s tan c e space w i r e s space i n space t h e space t w o space g a p s space o f space space a space m e t r e space space b r i d g e space comma space t h e space b a l a n c e space p o i n t space space w a s space f o u n d space t o space b e space 1 divided by 3 space m space f r o m space t h e space z e r o space e n d . w h e n space a space 6 capital omega space c o i l space i s space c o n n e c t e d space i n space s e r i e s space w i t h space t h e space s m a l l e r space o f space t h e space t w o space r e s i s tan c e s space comma space t h e space b a l a n c e d space p o i n t space i s space s h i f t e d space t o space 2 divided by 3 space m f r o m space t h e space s a m e space e n d space. space f i n d space t h e space r e s i s tan c e space o f space t h e space t w o space w i r e s space." align="middle" /></div>

Asked by yash.bisht9910 5th June 2015, 2:07 PM
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Q- Two charges +3Q and -2Q placed at (a,0) and (4a,0) respectively. What is the flux emanating out of the sphere of radius 3a taking 0 as the origin?

Asked by Subhashree Lenka 23rd May 2015, 11:34 PM
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Q- Four charges of same magnitude and same sign are palced at the corner of a square of side 0.1m . What is the electric field intensity at the centre of the square?

Asked by Subhashree Lenka 23rd May 2015, 11:17 PM
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In a meter bridge, the null point is found at a distance of 40 cm from A. If a resistance of 12Ω is connected in parallel with S, the null point occurs at 50.0 cm. from A. Determine the values of R and S.

Asked by Topperlearning User 28th April 2015, 12:54 PM
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Write the principle of working of a potentiometer. Describe briefly, with the help of a circuit diagram, how a potentiometer is used to determine the internal resistance of a given cell.

Asked by Topperlearning User 28th April 2015, 12:45 PM
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A potentiometer wire of length 1 m is connected to a driver cell of emf 3 V as shown in the figure. When a cell of 1.5 V emf is used in the secondary circuit, the balance point is found to be 60 cm. On replacing this cell and using a cell of unknown emf, the balance point shifts to 80 cm (i) Calculate unknown emf of the cell. (ii) Explain with reason, whether the circuit works; if the driver cell is replaced with a cell of emf 1 V. (iii) Does the high resistance R, used in the secondary circuit affect the balance point? Justify your answer.

Asked by Topperlearning User 28th April 2015, 12:43 PM
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A 10 m long wire of uniform cross-section and 20 Ω resistance is used in a potentiometer. The wire is connected in series with a battery of 5 V along with an external resistance of 480 Ω. If an unknown emf E is balanced at 6.o m length of the wire, calculate: 3 (i) the potential gradient of the potentiometer wire (ii) the value of unknown emf E

Asked by Topperlearning User 28th April 2015, 12:41 PM
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(a) State the working principle of a potentiometer. With the help of the circuit diagram, explain how a potentiometer is used to compare the emf's of two primary cells. Obtain the required expression used forcomparing the emfs. (b) Write two possible causes for one sided deflection in a potentiometer experiment. Or (a) State Kirchhoff's rules for an electric network. Using Kirchhoff's rules, obtain the balance condition in terms of the resistances of four arms of Wheatstone bridge. (b) In the meterbridge experimental set up, shown in the figure, the null point 'D' is obtained at a distance of 40 cm from end A of the meterbridge write. If a resistance of 10 Ω is connected in series with R1, null point is obtained at AD = 60 cm. Calculate the values of R1 and R2.

Asked by Topperlearning User 28th April 2015, 11:06 AM
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In a meter bridge, the null point is found at a distance of 40 cm from A. If a resistance of 12 Ωis connected in parallel with S, the null point occurs at 50.0 cm from A. Determine the values of R and S.

Asked by Topperlearning User 28th April 2015, 11:02 AM
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Write the principle of working of a potentiometer. Describe briefly, with the help of a circuit diagram, how a potentiometer is used to determine the internal resistance of a given cell.

Asked by Topperlearning User 28th April 2015, 10:48 AM
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A 10 m long wire of uniform cross- section and 20 Ω resistance is used in a potentiometer. The wire is connected in series with a battery of 5 V along with an external resistance of 480 Ω. If an unknown emf ε is balanced at 6.0 length of the wire,calculate : (i) the potential gradient of the potentiometer wire. (ii) The value of unknown emf ε.

Asked by Topperlearning User 28th April 2015, 10:45 AM
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(i) Calculate the equivalent resistance of the given electrical network between points A and B. (ii) Also calculate the current through CD and ACB if a 10 V dc source is connected between points  A and B and the value of R 2 Ω.

Asked by Topperlearning User 28th April 2015, 10:43 AM
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Why do we prefer a potentiometer to measure the emf of a cell rather than a voltemeter ?

Asked by Topperlearning User 28th April 2015, 10:41 AM
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In a potentiometer experiment the balancing with a cell is at length 140 cm. On shunting the cell with a resistance of 5 Ω, the balancing length becomes 100 cm. What is the internal resistance of the cell?

Asked by Topperlearning User 28th April 2015, 10:33 AM
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Why the emf of the driver cell in the potentiometer experiment is greater than the emf of the cell to be measured?

Asked by Topperlearning User 28th April 2015, 10:29 AM
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(i) Why the Wheatstone bridge method is more accurate than the other methods of measuring the resistances? (ii) When the balance point is obtained in the potentiometer the current is drawn from which battery?

Asked by Topperlearning User 28th April 2015, 10:22 AM
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The force on an electron in a potentiometer wire is 3.2 X 10-19 N. The length of the wire is 6 m. What is the e.m.f of the battery connected across the wire?

Asked by Topperlearning User 28th April 2015, 10:17 AM
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State the uses of potentiometer

Asked by Topperlearning User 28th April 2015, 10:12 AM
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The potential gradient along the length of uniform wire is 20 Vm-1. The length of wire is 1m. What is the potential difference across two points on the wire separated by distance 40 cm?

Asked by Topperlearning User 28th April 2015, 10:12 AM
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A potentiometer wire is 5 m long and a potential difference of 6 V is maintained between its ends. Find the emf of a cell which balances against a length of 180 cm of the potentiometer wire.

Asked by Topperlearning User 28th April 2015, 10:11 AM
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What do you mean by sensitivity of potentiometer? How can we increase the sensitivity of potentiometer?

Asked by Topperlearning User 28th April 2015, 9:58 AM
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Why do we prefer a potentiometer of longer length for getting the accurate readings?

Asked by Topperlearning User 28th April 2015, 9:54 AM
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Draw a circuit diagram to compare the emf of two primary cells. Write the formula used. How can the sensitivity of a potentiometer be increased. OR Draw the circuit diagram of potentiometer which can be used to determine the internal resistance (r) of a given cell of emf (E). Explain with the help of this diagram a method to find the internal resistance of a primary cell. Give reasons why potentiometer is superior to voltmeter for determining internal resistance.

Asked by Topperlearning User 28th April 2015, 9:49 AM
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two galvanometer a and b requires 3ma and 6ma to produce the same deflection of 10 divisions then

Asked by Mendy 13th April 2015, 1:17 PM
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Q.What is the effect of changing the resistance of primary circuit and secondary circuit on the balancing length of a potentiometer?

Asked by Ravi consul 4th March 2015, 6:41 PM
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<div>Q.In series combination of power</div> <div>&nbsp; &nbsp;Let two appliances be connected in series combination with resistances R and S connected to a battery of emf E and current in the circuit be I.</div> <div>So let equivalent circuit has resistance P</div> <div>&nbsp; &nbsp; &nbsp;In series,</div> <div>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; P=R+S</div> <div>Multiplying both sides by&nbsp;<img class="Wirisformula" src="https://images.topperlearning.com/topper/tinymce/integration/showimage.php?formula=546d1ab7dcb516407688c767e82f3843.png" alt="I squared" align="middle" /></div> <div>SO &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<img class="Wirisformula" src="https://images.topperlearning.com/topper/tinymce/integration/showimage.php?formula=546d1ab7dcb516407688c767e82f3843.png" alt="I squared" align="middle" />P=<img class="Wirisformula" src="https://images.topperlearning.com/topper/tinymce/integration/showimage.php?formula=546d1ab7dcb516407688c767e82f3843.png" alt="I squared" align="middle" />R+<img class="Wirisformula" src="https://images.topperlearning.com/topper/tinymce/integration/showimage.php?formula=546d1ab7dcb516407688c767e82f3843.png" alt="I squared" align="middle" />S</div> <div>Hence &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;equivalent power =&nbsp;<img class="Wirisformula" src="https://images.topperlearning.com/topper/tinymce/integration/showimage.php?formula=cce6ebff9dba7b3e77d9c3c5fa047f69.png" alt="P subscript R" align="middle" />+<img class="Wirisformula" src="https://images.topperlearning.com/topper/tinymce/integration/showimage.php?formula=2ff5802dc80e3c1d43d29e26bc30258b.png" alt="P subscript S" align="middle" />. &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; [power=<img class="Wirisformula" src="https://images.topperlearning.com/topper/tinymce/integration/showimage.php?formula=546d1ab7dcb516407688c767e82f3843.png" alt="I squared" align="middle" />resistance]</div> <div>what's wrong in this??????</div>

Asked by Ravi consul 4th March 2015, 6:38 PM
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at great distance from an electric dipole the electric field strength due to the dipole varies with distance r as (ans.1/r3) pls explain how?

Asked by Nidhi 27th December 2014, 1:37 PM
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Give two possible causes for one sided deflection in the potentiometer experiment. how can you identify each cause ?

Asked by Shubham Jain 22nd November 2014, 4:27 PM
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what are the two causes of one sided deflection in galvanometer in potentiometer experiment?how can you identify each fault ? how can you rectify them?

Asked by Shubham Jain 21st November 2014, 2:40 PM
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why do all appliances or devices get heatned up due to excessive?

Asked by Suhas v 4th October 2014, 6:48 PM
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what is meant by a post office box? and menntion its proper uses.

Asked by Sagar krishna 16th May 2014, 7:33 PM
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