7. A single resistor is connected across the terminals of a battery. Which the e

Question

7. A single resistor is connected across the terminals of a battery. Which the electric power dissipated in the resistor unchanged? one or more of the following changes leaves (A) Doubling the voltage and decreasing the current by a factor of two. (B) Doubling the voltage and increasing the resistance by a factor of four (C) Doubling the current and decreasing the resistance by a factor of four (a) A, B, C (b) A,B (e) B,C (d) A, C (e) B 8. An electron traveling duc east in a region that contains only a magnetic field experiences a force that is directed downward. What is the direction of the magnetic field (a) south (b) north (c) down ward(d st e) upward 9. Which one of the following statements concerning the magnetic force on a charged particle in a magnetic field is true? (a) The magnitude of the force is largest when the particle is not moving (b) The force is zero if the particle moves perpendicular to the field (c) The magnitude of the force is largest when the particle moves perpendicular to the direction of the magnetic field (d) The force depends on the component of the particle's velocity that is parallel to the field (e) The force acts in the direction of motion for a positively charged particle. 10. Each of the four phasor diagrams represents a different circuit. Vs and lo represent, respectively, the maximum voltage of the generator and the curent in the circuit. Which circuit contains only a resistor? I 1. The drawing shows four situations in which a negatively charged particle is moving with a velocity v through a magnetic field B. In each case, the magnetic field is directed into the page (away from you), and the velocity is directed to the left. In only one of these drawings is the magnetic force F physically reasonable. Which one is it? B (ie to the pape)B (in to the page) (a) B Cin to the page) FC?n to the page) 12. An ac voltage source that has a frequency fis connected across the terminals of an inductor. Which one of the following statements correctly indicates the effect on the inductive reactance when the frequeney is increased to 4 (a) The inductive (c) The inductive reactance is unchanged (e) The inductive reactance increases by a factor of four (b) The inductive reactance decreases by a factor of four (d) The inductive reactance decreases by a factor of eight. reactance increases by a factor of eight

Explanation / Answer

7. Option (c) is correct.

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8. Using right hand palm rule , direction of magnetic field must to the south.

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9. Option (c) is correct.

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10. In resistor voltage and current are always in same phase, so option (d ) is correct.

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11 again using right hand palm rule, force directed on charge particle is downwards, so optio .(d) is correct.

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12 inductive reactance increases by the factor of 4.

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Comment in case any doubt..goodluck

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