12. How would the amount of fuel required to send a spacecraft from Earth to the Moon compare with the amount needed to send the same spacecraft from the Moon back to Earth. Explain. (Numerical values not required) [2 marks] 13. An oscilloscope is a device that deflects a beam of electrons vertically and horizontally across a screen. Its many applications (eg electrocardiography} rely on high sensitivity to electric potential difference. a] How can we deflect the beam of electrons in the oscilloscope vertically, whether upward or downward, by various amounts? [2 marks] b} How can we deflect the beam horizontally from left to right and then horizontally again, more quickly, from right to left? [2 marks] c) If an oscilloscope is to be used to monitor the heartbeat of a patient, what will determine the amount of vertical and horizontal deflection of the electrons? [2 marks]