The output of `OR` gate is `1`

Options

A. only if both inputs are zero
B. if either or both inputs are 1
C. only if both inputs are 1
D. if either input is zero

Answer

To solve the problem regarding the output of an OR gate being 1, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the OR Gate Functionality**:
The OR gate is a digital logic gate that outputs true (1) if at least one of its inputs is true (1). The output can be expressed as:
\[ Y = A + B \]
where \(Y\) is the output and \(A\) and \(B\) are the inputs.

2. **Identify the Conditions for Output to be 1**:
For the output \(Y\) to be 1, at least one of the inputs \(A\) or \(B\) must be 1. This can be summarized as:
- If \(A = 1\), then \(Y = 1\).
- If \(B = 1\), then \(Y = 1\).
- If both \(A = 1\) and \(B = 1\), then \(Y = 1\).
- The only case where \(Y = 0\) is when both \(A\) and \(B\) are 0.

3. **Evaluate the Given Options**:
Given the options:
- **Option 1**: Only if both inputs are 0. (This is incorrect as \(Y\) would be 0 in this case.)
- **Option 2**: If either or both inputs are 1. (This is correct as \(Y\) would be 1 in this case.)
- **Option 3**: Only if both inputs are 1. (This is incorrect as \(Y\) can still be 1 if only one input is 1.)
- **Option 4**: If either input is 0. (This is incorrect as \(Y\) could still be 1 if the other input is 1.)

4. **Conclusion**:
The correct answer is **Option 2**: If either or both inputs are 1, the output of the OR gate will be 1.