Author: Lou Bloomfield

How does a heat lamp work and could it be harmful to the eyes of pets from exten…

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How does a heat lamp work and could it be harmful to the eyes of pets from extended exposure? — DM, Osceola, IA

A heat lamp is much like a normal incandescent lamp, except that the heat lamp’s large filament operates at a much lower temperature. Because of this lower temperature, the filament emits relatively little visible light. Instead, it emits mostly invisible infrared light. While you can’t see infrared light, you can feel it as heat. Looking at a heat lamp is no more dangerous than looking at the glowing coals in a fireplace. Their thermal radiation heats your skin and the surfaces of your eyes, and is likely to make you uncomfortable enough to turn away before it causes real damage. In contrast, ultraviolet light from a sunlamp can injure your skin and eyes without causing any immediate pain—it’s only much later that you feel the sunburn on your skin and corneas. That’s why a heat lamp is relatively safe while a sunlamp is not.

How does air pressure affect the distance a soccer ball can be kicked?

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How does air pressure affect the distance a soccer ball can be kicked? — SR, Pittsburgh, PA

In general, the greater the air pressure, the greater the air resistance. As the soccer ball moves through the air, the air in front of it experiences a rise in air pressure and pushes the ball in the direction opposite its motion. While there are various other changes in air pressure around the ball’s surface, this rising pressure in front of the ball remains largely unbalanced and it slows the ball down. The higher the air pressure was to start with, the greater its rise in front of the ball and the stronger the backward push of air resistance. Thus if you were to play soccer in the Rocky Mountains, where the air pressure is much less, you’d be able to kick the ball significantly farther.

Is it possible to eat a microwave while you eat food that was cooked in the micr…

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Is it possible to eat a microwave while you eat food that was cooked in the microwave oven? – PTW

Not one that came from the microwave oven. Microwaves are all around us and are completely innocuous. Your body emits weak microwaves all the time, as part of its thermal radiation! Like light, microwaves don’t remain still in objects so you can’t eat one that was put in the food by the oven.

I am interested in finding out if and what materials affect magnetic fields.

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I am interested in finding out if and what materials affect magnetic fields. — HLD, Jacksonville, FL

Magnetic fields are associated with lines of magnetic flux, invisible structures that stretch between north and south magnetic poles or that curve around on themselves to form complete loops. Unless a material has its own north or south magnetic poles, it can’t terminate the magnetic flux lines and can have only small effects on magnetic fields. The few materials that do affect magnetic fields substantially are ones such as iron or steel that are intrinsically magnetic and that can easily develop strong north and south magnetic poles. These magnetic materials can significantly shift the paths of the magnetic flux lines. If you put an iron or steel box in a magnetic field, the flux lines will tend to travel through the walls of the magnetic box. As a result, there will be few magnetic flux lines inside the box and almost no magnetic field. This effect is used to shield sensitive equipment such as the picture tubes in televisions from magnetic fields.

How can we clean the microwave oven? – PTW

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How can we clean the microwave oven? – PTW

Since the cooking chamber of a microwave oven doesn’t get hot, there is no way to make a “self-cleaning” microwave oven. Instead, you have to clean it by hand with a sponge and perhaps a little soapy water. As long as you get the soap or any other cleaning agents out, you can clean the cooking chamber just as you’d clean the top of a stove.

If the condenser in a microwave is bad, what is the most likely reaction the mic…

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If the condenser in a microwave is bad, what is the most likely reaction the microwave generator will exhibit? — IF, Bakersfield, CA

According to a reader, most microwave oven capacitors have fuses in them so that when they fail, they usually become open (they lose all of their ability to store separated charge and behave as a simple open circuit). You’d need a capacitor checker to find this open circuit within the capacitor.

How can we measure magnetic fields or magnetic potentials of solvent atoms that …

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How can we measure magnetic fields or magnetic potentials of solvent atoms that reside interstitially inside solid solutes? — DR, Tampa, FL

You can measure the magnetic fields in which certain atoms reside with the help of nuclear magnetic resonance (NMR). This technique examines the magnetic environment of the atom’s nucleus by determining how much energy it takes to change the orientation of the nucleus. Since the nucleus is itself magnetic, it tends to align with any magnetic field—like a compass. The stronger that magnetic field, the harder it is to flip the nucleus into the wrong direction.

What happens when matter and anti-matter collide? Do they just destroy each othe…

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What happens when matter and anti-matter collide? Do they just destroy each other? I thought that matter couldn’t be created or destroyed? – S

As Einstein’s famous formula points out, mass and energy are equivalent in many respects. In most situations, mass is conserved and so is energy. But at the deepest level, it’s actually the sum of those two quantities that’s conserved. When matter and anti-matter collide, they often annihilate one another and their mass/energy is converted into other forms. For example, when an electron and an anti-electron (a positron) collide, they can annihilate to produce two or more photons of light. There is no fundamental law that prevents matter from being created or destroyed but there is a fundamental law that mass/energy must be conserved. In this case, the masses of the electron and positron become energy in the massless photons. Overall, mass/energy has been conserved but what was originally mass has become energy. The fact that when matter and anti-matter annihilate, the product is usually energy, makes this mixture attractive as a possible super-rocket fuel. But don’t hold your breath; anti-matter is incredibly difficult to make or store.

How does ultrasound detect cracks or imperfections in metal? Is this to do with …

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How does ultrasound detect cracks or imperfections in metal? Is this to do with density or is it just reflecting off surfaces? — PA, Essex, UK

Like all waves, ultrasound reflects whenever it passes from one material to another and experiences a change in speed (or more accurately, a change in impedance). Any inhomogeneity in a metal is likely to change the speed of sound in that metal and will cause some amount of sound reflection. With the proper instruments emitting sound and detecting the reflected sound, it’s possible to image the imperfections. The same technique is used in medical ultrasound to image organs or fetuses, and even to image the insides of the earth.