Mathematically, ‘Q’ is directly proportional to ‘C’ keeping ‘V’ constant. The latter proves the same point.
In question 3, the diagram has a voltage source and a resistance, in the form of a lamp. In order for the lamp to light a complete circuit in order for the electric current to flow is necessary. The electrons flow from high positive potential to low negative potential (in conventional current) through a low resistance path. In case, the circuit is not complete, the electrons encounter a high resistance path i.e air or vacuum. The latter causes no current to flow leading to the lamp not lighting. Mathematically, the ohms law provides reason. Ohms law is stated as:
The current drawn from a battery is linked with the potential difference across the battery. When two batteries were attached the potential difference was twice as much as when a single battery was connected. Applying the latter fact with Ohms law:
Since the same toy car is used each time, we can safely assume that ‘R’ is constant. This gives the relation, I is directly proportional with V. When V is halved then I must also be halved. Therefore, option B being correct.
Substituting the values for the blender and car vacuum separately we find that the power drawn for the blender is 480W while power drawn by the car vacuum is 60W. And so, we can conclude that the blender draws more