Explanation: To understand the time difference between Greenwich Mean Time (GMT) and Indian Standard Time (IST), it is essential to know that IST is 5.5 hours ahead of GMT. This means that when it is 7:30 PM on January 16 in Greenwich, it will be 5.5 hours later in Chennai.
Let's break down the calculation step-by-step:
1. **Identify the GMT time**: The given time is 7:30 PM on January 16 in GMT.
2. **Add the time difference**: IST is 5.5 hours ahead of GMT. Therefore, we need to add 5.5 hours to the GMT time.
3. **Perform the addition**:
- Adding 5 hours to 7:30 PM results in 12:30 AM on January 17.
- Adding the remaining 0.5 hours (30 minutes) to 12:30 AM results in 1:00 AM on January 17.
Thus, when it is 7:30 PM on January 16 in GMT, it will be 1:00 AM on January 17 in IST.
It is important to note that when adding the time difference, if the result crosses midnight, the date changes. In this case, adding 5.5 hours to 7:30 PM on January 16 results in a time that is past midnight, hence the date changes to January 17.
Understanding time zones and their differences is crucial for various applications, including international travel, scheduling, and global communication. The concept of time zones helps in standardizing time across different regions of the world, making it easier to coordinate activities and events across different geographical locations.
In summary, the correct answer is 1:00 AM on January 17 in Chennai when it is 7:30 PM on January 16 in Greenwich. This is because IST is 5.5 hours ahead of GMT, and the time difference must be correctly accounted for, including the date change if necessary.