Heat & Temperature
📚 Topic Overview: Heat & Temperature
This topic explains temperature, measurement methods, units used, and various thermometers.
These concepts appear repeatedly in national and state competitive exams because they connect
to daily-life applications in health, weather, cooking, laboratories, and safety.
1. Temperature
Concept / Theory
Temperature is a measure of how hot or cold an object is. It depends on the
average kinetic energy of particles. Higher
temperature → faster particle movement.
Analogy / Examples
- Boiling water has faster-moving molecules than tap water.
Key Points
- Temperature is a physical quantity.
- Measured using thermometers.
- Different scales: Celsius, Fahrenheit, Kelvin.
| English | Telugu |
|---|---|
| Temperature | ఉష్ణోగ్రత |
| Heat | ఉష్ణం |
| Kinetic Energy | చలన శక్తి |
Doctors check body temperature to identify fever. A slight rise in temperature
indicates increased internal activity in the body.
Remember: Temperature ≠ Heat. Temperature measures how hot,
while heat is total energy.
2. Measuring Temperature
Concept / Theory
Temperature is measured using thermometers based on expansion of liquids
(like mercury or alcohol) or electronic sensors. The reading is taken from
the scale marked on the thermometer.
Measurement Steps
- Place bulb in contact with object.
- Wait till liquid column stops rising.
- Read scale carefully at eye level.
Common Errors to Avoid
- Do not read at an angle (parallax error).
- Ensure thermometer is clean.
- Do not shake quickly (may break).
| English | Telugu |
|---|---|
| Thermometer | ఉష్ణామాపకము |
| Bulb | బల్బు |
| Scale | మాపు పట్టిక |
Food inspectors measure temperature of milk samples to ensure safety during transport.
Reading is always taken at eye level to avoid parallax error.
3. Units of Temperature
Concept / Theory
The three main units used to measure temperature are:
Celsius (°C),
Fahrenheit (°F), and
Kelvin (K).
Comparison Table
| Scale | Lower Fixed Point | Upper Fixed Point |
|---|---|---|
| Celsius | 0°C | 100°C |
| Fahrenheit | 32°F | 212°F |
| Kelvin | 273 K | 373 K |
Conversion Formulas
| Conversion | Formula |
|---|---|
| °C → °F | (°C × 9/5) + 32 |
| °F → °C | (°F − 32) × 5/9 |
| °C → K | °C + 273 |
| English | Telugu |
|---|---|
| Celsius | సెల్సియస్ |
| Fahrenheit | ఫారన్హీట్ |
| Kelvin | కెల్విన్ |
Weather department uses Celsius for forecasting, while laboratories prefer Kelvin for scientific calculations.
Remember: 0 K = −273°C (Absolute zero).
4. Types of Thermometers
Concept / Theory
Different thermometers are used for different purposes. Their design depends on
the required range and application.
Comparison Table
| Type | Use | Range |
|---|---|---|
| Clinical | Body temperature | 35°C to 42°C |
| Laboratory | Experiments | −10°C to 110°C |
| Digital | Medical use | Wide range |
| Infrared | Contactless measurement | Varies |
| English | Telugu |
|---|---|
| Clinical Thermometer | వైద్య ఉష్ణామాపకము |
| Laboratory Thermometer | ప్రయోగశాల ఉష్ణామాపకము |
| Digital Thermometer | డిజిటల్ ఉష్ణామాపకము |
In pandemic situations, infrared thermometers are used for quick scanning
at schools, offices, and public places.
Clinical thermometers have a kink to prevent mercury from falling back.
5. Exam Tips & Tricks + Memory Sheet + Sample Questions
Memory / Formula Sheet
- °C → °F: (°C × 9/5) + 32
- °F → °C: (°F − 32) × 5/9
- °C → K: + 273
- Clinical thermometer range: 35°C–42°C
- Laboratory thermometer has no kink
Sample Questions
- Why is a kink provided in clinical thermometers?
- Which temperature scale begins at absolute zero?
- Why does a laboratory thermometer require constant holding?
- Convert 50°C to Fahrenheit.
- Why is Kelvin used in scientific studies?
Most questions mix **thermometers + units + conversions**. Practice mental
calculations for °C ↔ °F conversions.