Which of the following options is correct regarding the open-loop differential amplifier?

Explanation:

Open-Loop Differential Amplifier

Definition: An open-loop differential amplifier is an electronic amplifier that amplifies the difference between two input voltages without any feedback loop. It is commonly used in various analog circuits to amplify small differential signals. The term "open-loop" indicates that there is no feedback path from the output back to the input of the amplifier. 

Analysis of Other Options:

Option 1: "Input is applied at the inverting terminal only." This statement is incorrect because an open-loop differential amplifier requires inputs to be applied to both the inverting and non-inverting terminals to operate correctly. Applying input to only one terminal would not allow the amplifier to perform differential amplification.

Option 2: "Input is applied at non-inverting terminal only." Similar to Option 1, this statement is incorrect. An open-loop differential amplifier needs inputs at both the inverting and non-inverting terminals to function as intended.

Option 4: "Output is always zero irrespective of the input applied at terminals." This statement is incorrect because, in an open-loop differential amplifier, the output is highly dependent on the difference between the input voltages. Given the high gain, even a small input difference can produce a substantial output voltage.