Answer:potential difference is more or less like voltage. Using ohms, V=IR
Where V is Voltage
I is Current =0.4A
R is Resistance=20ohms
V=0.4*20
V=8V
Hence the potential difference will be 8V.
ii) V=0.4*30
V=12V
Explanation:
The voltage of potential difference is directly proportional to the current and the resistance. So if one increase or decrease, it will have impact on the other.
From the calculations, when the resistance increase, the voltage will increase to appreciate the change.
A variable is a letter so just be like
13a or something like that
Explanation:
It is given that,
Voltage, 
De broglie wavelength in terms of voltage is given by :
m and e are the mass and charge on electron. So,
So, the De broglie wavelength of an electron is 1.53 meters. Hence, this is the required solution.
