Question$\qquad$ A. Magnetic field has only magnitude. B. Magnetic field $B$ is inversely proportional to the distance $r$. C. The force is repulsive if the current carrying wires are parallel. D. The force is attractive if the currents carrying wires are anti parallel.
10. An electric heater is constructed by applying potential difference of 120 V to Nichrome wire has a total resistance of $80 \Omega$. What is the power raiting of the heater? A. 15 W B. $1.8 \times 10^{3} \mathrm{~W}$ C. 280 W D. $1.5 \times 10^{3} \mathrm{~W}$ $\qquad$
11. Which of the following is correct statement, when the direction of current is upward? A. the magnetic field is clockwise A. Which C. The magnetic force is into the page - 9. B. the magnetic field is anti clockwise D. all $\qquad$ B. the magnetic field is and intersed in a vessel containing melting indium, $50 \Omega$ at $20^{\circ} \mathrm{C}$. When immersed its resistance increases to $76.8 \Omega$. What is the melting point of the indium? (Use $\alpha=3.92 \times 10^{-3} \mathrm{C}^{-1}$ ) D. $1 \times 10^{40} \mathrm{C}$