You can write the equation in 3 different ways, depending on which quantity you want to be the dependent variable. Any one of the three forms can be derived from either of the other two with a simple algebra operation. They're all the same relationship, described by "Ohm's Law".
==> Current = (potential difference) / (resistance)
==> Potential difference = (current) x (resistance)
==> Resistance = (potential difference) / (resistance)
25/1500 is equal to 0.8/x
0.8*1500 is equal to 1200
1200/25 is equal to 48 N
Generally, the internal resistance of the new battery is small, about 0.2 euros, while the old battery is large, close to 1 euro ，
Time taken to complete one oscillation for a pendulum is Time Period, T = 0.5 s
Frequency of the pendulum oscillation = 1 / Time Period => f = 1 / T = 1 / 0.5
Frequency f = 2 Hz
