Questions

Brightness of bulb depends on both voltage and current. The brightness depends on power.

Since we know that  Power (P) = Voltage x Current = V I

So whether you increase the current or the voltage the brightness will increase.

Example Illustration:

 If you connect a long bulb and a round bulb in series, the long bulb glows but the round bulb does not. Both of them have the same current flowing through them (they are in series) but the long bulb has a greater voltage across it because it has more resistance (even though V= IR is not obeyed exactly, voltage drop does depend on the resistance). If you connect a round bulb and a long bulb in parallel, however, it is the round bulb that is brighter because now the voltage across both bulbs is the same but the current is larger through the round bulb (smaller resistance).

Hence, the brightness of a bulb depends on power i.e, both voltage and current.

The answer here is 1.

Logic Followed in the given puzzle ::

The logic here is the number of circles in each 4 digit number mentioned.

8801 has 5

5261 has 1

and so on

Computer was invented by Charles Babbage.

The First Mechanical Computer Designed by Charles Babbage, a British mathematician was called as Analytical Engine which resembles today's modern machines  between 1833 and 1871.

Emergence of two great power blocs:

Two power blocs came into existence after the Second World War. The United States of America and Soviet Russia became two Super Powers. They tried to dominate over other countries in their own way. Ultimately, it gave a headache to the world.

The Cold War was a state of political and military tension after World War II between powers in the Western Bloc (the United States, its NATO allies and others) and powers in the Eastern Bloc (the Soviet Union and its allies in the Warsaw Pact).