Related InterviewSolutions

• The wires which connect the battery of an automobile to its starting motor carry a current of `300A` (for a short time). What is the force per unit length between the wires if they are `70cm` long and `1*5cm` apart? Is the force attractive or repulsive?
• Two moving coil meters `M_1` and `M_2` have the following particulars: `R_1=10Omega`, `N_1=30`, `A_1=3*6xx10^-3m^2`, `B_1=0*25T`, `R_2=14Omega`, `N_2=42`, `A_2=1*8xx10^-3m^2`, `B_2=0*50T` (The spring constants are identical for the two metres). Determine the ratio of (a) current sensitivity and (b) voltage sensitivity of `M_2` and `M_1`.
• A uniform magnetic field of `3000G` is established along the positive z-direction. A rectangular loop of sides `10cm` and `5cm` carries a current `12A`. What is the torque on the loop in the different cases shown in the figure. What is the force on each case? Which case corresponds to stable equilibrium?
• A square coil of side `10cm` consists of 20 turns and carries a current of 12A. The coil is suspended vertically and normal to the plane of the coil makes an angle of `30^@` with the direction of a uniform horizontal magnetic field of magnitude `0*80T`. What is the magnitude of torque experienced by the coil?
• A straight wire carrying a current of `12A` is bent into a semicircular arc of radius `2*0cm` as shown in figure. Consider the magnetic field `vecB` at the centre of arc. (a) What is the magnetic field due to the staight segments? (b) In what way the contribution to `vecB` from the semicircle differs from that of a circular loop and in what way does it resemble? (c) Would your answer be different if the wire were bent into a semicircle arc of the same radius but in the opposite way as shown in figure
• A straight wire of mass 200 g and length 1.5 m carries a current of 2 A. It is suspended in mid-air by a uniform horizontal magnetic field B. What is the magnitude of the magnetic field?
• What is the radius of the path of an electron (mass `9 xx 10^(-31)` kg and charge `1.6 xx 10^(-19)C)` moving at a speed of `3 xx 10^(7)m//s` in a magnetic field of `6 xx 10^(-4)T` perpendicular to it? What is its frequency? Calculate its energy in `keV.(1eV = 1.6 xx 10^(-19)J)`.
• If the magnetic field is parallel to the positive y-axis and the charged particle is moving along the positive x-axis (Fig.), which way would the Lorentz force be for (a) an electron (negative charge), (b) a proton (positive charge).
• A current carrying circular loop is located in a uniform external magnetic field. If the loop if free to turn, what is its orientation of stable equilibrium? Show that in this orientation, the flux of the total field (external field + field produced by the loop) is maximum.
• In the circuit shown in figure, the current is to measured. What is the value of the current if the ammeter shown (i) is a galvanometer with a resistance `R_G=60*00Omega`. (ii) is a galvanometer described in (i) but converted to an ammeter by a shunt resistance `r_s=0*02Omega`, (iii) is an ideal ammeter with zero resistance?