Current Electricity · JEE Main previous year questions

2006 6 questions

1. Q652006 · 29 Apr 2006 · Shift 1

   The resistance of bulb filament is $100\Omega$ at a temperature of $100^{\circ }\mathrm{C}$. If its temperature coefficient of resistance be $0.005\mathrm{per}{}^{\circ }\mathrm{C}$, its resistance will become $200\Omega$ at a temperature of

   1. A.$300^{\circ }\mathrm{C}$
   2. B.$400^{\circ }\mathrm{C}$
   3. C.$500^{\circ }\mathrm{C}$
   4. D.$200^{\circ }\mathrm{C}$
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   Answer: B

2. Q662006 · 29 Apr 2006 · Shift 1

   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

   1. A.$\frac{P}{Q}=\frac{2R}{S_1+S_2}$
   2. B.$\frac{P}{Q}=\frac{R(S_1+S_2)}{S_1{S}_2}$
   3. C.$\frac{P}{Q}=\frac{R(S_1+S_2)}{2S_1{S}_2}$
   4. D.$\frac{P}{Q}=\frac{R}{S_1+S_2}$
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   Answer: B

3. Q742006 · 29 Apr 2006 · Shift 1

   In an $AC$ generator, a coil with $N$ turns, all of the same area $A$ and total resistance $R$, rotates with frequency $\omega$ in a magnetic field $B$. The maximum value of $emf$ generated in the coil is

   1. A.$N.A.B.R.\omega$
   2. B.$N.A.B$
   3. C.$N.A.B.R.$
   4. D.$N.A.B.\omega$
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   Answer: D

4. Q772006 · 29 Apr 2006 · Shift 1
   
   1. A.$1/e\mathrm{A}$
   2. B.$e\mathrm{A}$
   3. C.$0.1\mathrm{A}$
   4. D.$1\mathrm{A}$
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   Answer: A

5. Q902006 · 29 Apr 2006 · Shift 1

   A material 'B' has twice the specific resistance of 'A'. A circular wire made of 'B' has twice the diameter of a wire made of 'A'. Then for the two wires to have the same resistance, the ratio ${\ell }_B/{\ell }_A$ of their respective lengths must be

   1. A.2
   2. B.1
   3. C.$\frac{1}{2}$
   4. D.$\frac{1}{4}$
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   Answer: A

6. Q912006 · 29 Apr 2006 · Shift 1

   The Kirchhoff's first law ($\sum i=0$) and second law ($\sum iR=\sum E$), where the symbols have their usual meanings, are respectively based on

   1. A.conservation of charge, conservation of energy
   2. B.conservation of charge, conservation of momentum
   3. C.conservation of energy, conservation of charge
   4. D.conservation of momentum, conservation of charge
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   Answer: A