The first overtone frequency of an open organ pipe is equal to the fundamental frequency of a closed organ pipe. If the length of the closed organ pipe is 20 cm. The length of the open organ pipe is _____________ cm.

The equivalent capacitance between points A and B in below shown figure will be __________ $$\mu$$F.

A resistor develops 300 J of thermal energy in 15 s, when a current of 2 A is passed through it. If the current increases to 3 A, the energy developed in 10 s is ____________ J.

The total current supplied to the circuit as shown in figure by the 5 V battery is ____________ A.