In modern cellular systems, the radio frequency output power of a powerful handheld mobile phone transmitter is typically of which approximate order of magnitude?

Introduction / Context:
This question gives an approximate idea of the radio frequency power transmitted by a powerful handheld mobile phone. While precise values depend on the standard, network, and region, it is still useful for students to know the order of magnitude. The transmit power affects coverage range, battery life, and potential electromagnetic exposure. However, mobile phones operate at relatively low power levels compared to base stations or broadcast transmitters.

Given Data / Assumptions:

We are talking about handheld mobile phones, not base stations or fixed transmitters.

The question is about powerful phones, so we consider their upper transmit power range.

Transmit power is expressed in terms of order of magnitude rather than an exact value.

Typical cellular standards allow power levels in the range of a few hundred milliwatts.

Options span from milliwatts to hundreds of watts, covering several orders of magnitude.

Concept / Approach:
Handheld mobile phones are designed to be battery powered and safe to use near the human body, so their transmit power is kept relatively low. In many cellular standards, maximum transmit power for handheld devices falls in the approximate range of 0.2 W to 1 W, which equals a few hundred milliwatts up to around one watt. Lower levels such as a few milliwatts would severely limit coverage distance, while tens or hundreds of watts are more appropriate for base stations and broadcast transmitters, not for small handheld devices.

Step-by-Step Solution:
Step 1: Recall from communication engineering that handheld mobile phones typically transmit in the sub watt range, on the order of a few hundred milliwatts.Step 2: Recognize that 1 mW or a few tens of milliwatts would be too low for reliable cellular coverage except at very short range.Step 3: Observe that tens or hundreds of watts are far above what a handheld device can safely and efficiently transmit.Step 4: Compare the options and identify the one that describes a few hundred milliwatts up to about 1 watt.Step 5: Select that option as it matches the practical upper transmit power of powerful handheld mobile phones.

Verification / Alternative check:
Typical specifications for handheld devices in systems such as GSM, UMTS, or LTE give maximum powers on the order of 20 dBm to 33 dBm depending on the band and class, which correspond roughly to 0.1 W to 2 W at most. Many phones operate at around 23 dBm to 30 dBm, which equals approximately 0.2 W to 1 W. These values fall squarely into the description of a few hundred milliwatts up to about one watt. This confirms that option C, which describes that order of magnitude, is the most accurate for exam purposes.

Why Other Options Are Wrong:
Option A, a few milliwatts, would be too weak for practical mobile communication except in very short range applications like some low power wireless sensors. Option B, a few tens of milliwatts, is still on the low side for typical cellular phone maximum power. Option D, tens of watts, corresponds more to base station or high power transmitters and would cause severe heating and battery problems in a handheld device. Option E, hundreds of watts, refers to large broadcast or radar transmitters and is completely unrealistic for mobile phones.

Common Pitfalls:
Students may confuse mobile phone transmit power with the much higher power levels used by base stations or by radio and television transmitters. Another pitfall is to assume that because mobile phones are small, their power must be of the same order as wireless headphones or small Wi Fi dongles, which often transmit at lower levels than powerful cell phones. To avoid these misunderstandings, remember that mobile phones operate roughly in the range of a few hundred milliwatts up to about one watt of RF power.

Final Answer:
The strength of the signal transmitted by a powerful handheld mobile phone is typically a few hundred milliwatts up to about 1 watt of radio frequency power.