Menu
Close
Sign up for NPL updates
Close
Sign up for NPL updates

For people, place, prosperity and planet, we deliver impact with measurement science.

Our use of cookies

We use necessary cookies to make our site work. We'd also like to set optional analytics cookies to help us improve it. We won't set optional cookies unless you enable them.

Necessary cookies

Necessary cookies enable core functionality such as security, network management, and accessibility. We do not use cookies for marketing purposes.

Analytics cookies

We utilise Google Analytics cookies to help us to improve our website by collecting information on how it's used.
Find out more

Resources

Questions and answers

Do you want to know more about metrology and the science of measurement?

Have you ever wanted to know the answers to the most popular questions about measurement or physics?  What is the difference between metrology and measurement? Why is the science of measurement important? What are the laws of physics? What is physics and why is it important? How is physics used in everyday life?

What is a leap second?

An occasional leap second adjustment ensures our clocks reflect the Earth's rotation speed as accurately as possible.

Find out more

What is net zero?

The UK has committed to bringing all greenhouse gas emissions to ‘net zero’ by 2050, but what does this mean?

Find out more

How are greenhouse gases measured?

Greenhouse gases in the Earth’s atmosphere are increasing. So how do we define and measure the greenhouse effect?

Find out more

How do scientists measure the temperature of the Earth

Many aspects of the earth’s temperature can be measured, each with their own relevance and techniques. 

Find out more

How and why do we measure the colour of the ocean?

What role does ocean colour play in measuring climate change?

Find out more

What is a National Metrology Institute?

NMIs realise, maintain and develop their country’s primary measurement standards.

Find out more

What’s the difference between metrology and measurement?

Both are fundamental to human activity, but what’s the difference?

Find out more

Is midnight 12am or 12pm?

The meaning of 12am,12pm, midday, midnight and the 24-hour clock

Find out more

Is there a difference between measurement 'accuracy' and 'uncertainty'?

When used in measurement it is vital to use the correct word

Find out more

When do the four British seasons dates officially begin?

There are no official definitions of the duration of spring, summer, autumn and winter, so what are the british seasons dates?

Find out more

Why does atmospheric pressure change with altitude?

Atmospheric pressure reduces with altitude for two reasons, both of which are related to gravity.

Find out more

What is the difference between density and specific gravity?

Both are used to describe mass and to compare substances

Find out more

Why is my radio-controlled clock not showing the correct time?

What can you do to ensure you receive the correct time?

Find out more

What is the scientific definition of a vacuum?

The definition of a vacuum is not precise but is commonly taken to mean pressures below, and often considerably below, atmospheric pressure.

Find out more

What are g-forces and are they caused by gravity?

The term g-force is used to convey values of force and acceleration.

Find out more

What is the SI unit of force?

Historically, there have been a variety of units of force and conversion factors.

Find out more

What are the differences between mass, weight, force and load?

We use these words on a daily basis, but do you really know the difference?

Find out more

How is air density determined?

Air density is used in many branches of science, engineering and industry andy can be measured in two broad categories, Indirect measurement or parametric method and Direct measurement.

Find out more

How do I convert between dew point and relative humidity?

There is no simple formula for converting between dew point and relative humidity.

Find out more

The difference between a transducer and a transmitter?

Both devices measure pressure, but what’s the difference?

Find out more

What is emissivity and why is it important?

What is emissivity? All objects at temperatures above absolute zero emit thermal radiation.

Find out more

What is a platinum resistance thermometer?

A platinum resistance thermometer (PRT) contains a piece of platinum wire, whose electrical resistance is proportional to temperature.

Find out more

How small is the world's smallest Christmas card?

The world's smallest Christmas card requires a powerful microscope just to see it, helping to unlock new battery and semiconductor technologies.

Find out more

What is platinum?

Platinum is one of the rarest and most precious metals. It is used to represent 70 year celebrations – birthdays, anniversaries and, recently, the Queen’s Jubilee.

Find out more

How hot is the hottest Christmas pudding?

NPL's temperature experts created a graphite Christmas pudding and placed it in our high-temperature furnace.

Find out more

You may also like

Want more detail? Delve into the subjects more deeply.

The SI units

 

Quantum

 

Graphene

 

NPLTime®

Contact us

Our research and measurement solutions support innovation and product development. We work with companies to deliver business advantage and commercial success.
Contact our Customer Services team on +44 20 8943 7070

Make a general enquiry