Think about these statements. (i) The emf in a turning generator coil is zero when its plane is at right angles to the field. (ii) In an LR circuit the current jumps at once to $\mathcal{E}/R$ when the switch is closed. (iii) A frame that moves wholly inside a uniform field feels no force from the field. (iv) A rod falling on rails with a resistor reaches a terminal speed. How many of them are correct?