A defibrillator is a device that delivers an electric charge through the heart of a patient whose heart is not beating properly. Medical staff practise using a defibrillator on a medical dummy. Fig. 7.1 shows the two contacts of a defibrillator connected to a medical dummy. The parts of the contacts that touch the dummy are metal, and when the defibrillator is in use, one contact is made strongly negatively charged while the other is made strongly positively charged. The contact handles are plastic, which is an electrical insulator.
(a(i))[1]
State how the internal structure of an electrical insulator is different from that of a conductor.
(a(ii))[2]
Suggest the reason the handles are made from an electrical insulator.
(b)[2]
Explain, in terms of the particles involved, how one contact becomes negatively charged and how the other contact becomes positively charged.
(c)[2]
Calculate the mean current in the dummy.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “In an insulator, electrons are fixed/tightly bound and there are no delocalised/free/mobile electrons” …