Assertion (A): When cathode temperature is increased from 2500 K to 2550 K, thermionic emission current may increase by about 50%. Reason (R): Thermionic emission current ∝ T2 e-Ew/kT.

• Both A and R are true and R is correct explanation of A
• Both A and R are true but R is not correct explanation of A
• A is true but R is false
• A is false but R is true