A pair of parallel conducting rails that are $12 mathrm{~cm}$ apart lies at right angles to a uniform magnetic field of $0.8 mathrm{~T}$ directed into the page, as shown in Figure $20-25 .$ A $15-Omega$ resistor is connected across the rails. A conducting bar is moved to the right at $2 mathrm{~m} / mathrm{s}$ across the rails. (a) What is the current in the resistor? (b) What direction is the current in the bar (up or down)? (c) What is the magnetic force on the bar?