If you could only see the lights in the circuit and the wires were covered from view, how could you determine the type of circuit the lights are arranged in?

Explanation:

you can determine the type of circuit through the intensity of the light because A) If all the lights are equal brightness, it is a series circuit. B) If all the lights are not equal brightness, it is a parallel circuit.

The type of the circuit can be determined by the brightness of light.

Explanation:

There may be three scenarios given below:  

i) If the brightness of all the lights is same then it is a series circuit. Because same current is flowing through each light causes equal brightness.

ii) If the brightness of all the lights is not same then it is a parallel circuit. This will happen when the resistance of lights is different. When resistance of lights will be same, equal current flow through each light and they have equal brightness. In this case it is difficult to find whether it is series or parallel circuit. To solve this problem, look at case (iii)

iii) Unscrew a light, if all lights get OFF it is a series circuit. If others lights remain ON it is a parallel circuit.

50 inches should be the resultant vector