BLACK+DECKER EM720CB7 Microwave Oven: Quick Cooking, Explained

The Everyday Miracle in Your Kitchen

Imagine this: You’ve had a long day, and you’re finally home, stomach rumbling. The thought of spending an hour cooking is daunting. Thankfully, there’s a device in your kitchen that can deliver a hot meal in minutes – the microwave oven. It seems almost magical, transforming cold leftovers into steaming deliciousness with the push of a button. But behind this everyday miracle lies a fascinating story of scientific discovery and clever engineering.

A Happy Accident: The History of the Microwave Oven

The microwave oven’s story begins not in a kitchen, but in a lab, with a man named Percy Spencer. Spencer, an American engineer working for Raytheon Corporation in the 1940s, was researching radar technology during World War II. Radar, which uses radio waves to detect objects, relied on a device called a magnetron to generate these waves.

One fateful day, while working near an active magnetron, Spencer noticed something peculiar: a chocolate bar in his pocket had melted. Intrigued, he conducted further experiments, placing popcorn kernels and then an egg near the magnetron. The popcorn popped, and the egg cooked (and exploded!), confirming his suspicion: the magnetron was emitting energy that could heat food. This accidental discovery paved the way for the first commercial microwave oven, the “Radarange,” released in 1947. It was a behemoth – nearly six feet tall, weighing over 750 pounds, and costing thousands of dollars. Thankfully, technology has come a long way.

Inside the Box: How Microwaves Work

So, how does this “magic box” actually work? Let’s break down the science:

• The Magnetron: The Heart of the Operation: At the core of every microwave oven is the magnetron, the very device that Percy Spencer was working with. It’s a specialized vacuum tube that converts electrical energy into microwave energy. Think of it as a highly sophisticated light bulb, but instead of producing visible light, it generates microwaves. Inside the magnetron, electrons are subjected to both electric and magnetic fields. This causes them to spin rapidly, generating electromagnetic waves in the microwave frequency range.

• Electromagnetic Waves: Energy in Motion: Microwaves are a form of electromagnetic radiation, just like radio waves, visible light, and X-rays. They all travel at the speed of light but differ in their wavelengths and frequencies. Microwaves have a relatively long wavelength (compared to light) and a frequency of about 2.45 gigahertz (GHz), which is 2.45 billion cycles per second. This specific frequency is crucial because it’s readily absorbed by water, fats, and sugars.

• Dielectric Heating: The Dance of the Molecules: This is where the magic of heating happens. Water molecules are “polar,” meaning they have a slightly positive charge on one end and a slightly negative charge on the other, like tiny magnets. When these molecules are exposed to the microwaves’ oscillating electromagnetic field, they try to align themselves with the field, constantly flipping back and forth. This rapid rotation and vibration create friction between the molecules, and this friction generates heat. This process is called dielectric heating. It’s important to note that the microwaves themselves aren’t hot; they cause the food to heat up from the inside out.

• Standing Waves and the Turntable: Ensuring Even Cooking: Inside the microwave oven’s cooking chamber, the microwaves bounce off the metal walls. This creates “standing waves,” which are patterns of high and low energy. If your food were stationary, some parts would be in the high-energy zones (and get very hot), while others would be in the low-energy zones (and remain cold). This is why most microwaves have a turntable. By constantly rotating the food, the turntable ensures that it passes through all parts of the microwave field, resulting in more even heating. Think of it like evenly toasting a marshmallow over a campfire – you need to rotate it to get all sides browned.

Meet the BLACK+DECKER EM720CB7: Convenience and Science Combined

The BLACK+DECKER EM720CB7 Digital Microwave Oven takes the science we’ve just discussed and packages it into a compact, user-friendly appliance. Let’s look at how its features relate to the principles of microwave cooking:

• Compact Design: Its dimensions (17.3” x 13.0” x 10.2”) make it ideal for kitchens with limited counter space, dorm rooms, or offices. This doesn’t affect the underlying science; it simply means the resonant cavity is smaller, designed for efficient heating of smaller food portions.

• Pre-programmed Settings: The EM720CB7 features convenient buttons for popcorn, potatoes, pizza, frozen vegetables, beverages, and dinner plates. These settings aren’t magic; they’re simply pre-set combinations of time and power level that have been optimized for those specific food types. The microwave’s internal programming takes into account the typical water content and density of these foods to ensure proper heating.

• 700 Watts: Power and Efficiency: The EM720CB7 operates at 700 watts. This refers to the power of the magnetron – its ability to generate microwaves. While higher-wattage microwaves (e.g., 1000W or 1200W) will cook food faster, 700 watts is perfectly sufficient for many common tasks like reheating leftovers, cooking frozen meals, and making popcorn. It’s also more energy-efficient. The key is to adjust cooking times. A simple rule of thumb is to increase the cooking time by approximately 30-50% compared to a 1000-watt microwave. So, if a recipe calls for 2 minutes at 1000 watts, you might cook it for 3 minutes at 700 watts.

• 10 Power Levels: This feature gives you fine-grained control over the cooking process. Lower power levels don’t mean the magnetron is producing weaker microwaves; instead, the magnetron cycles on and off, effectively reducing the average power delivered to the food. This is useful for delicate tasks like defrosting or melting chocolate, where you want to avoid overheating.

• Turntable: As we discussed earlier, the 10-inch turntable is essential for even cooking by ensuring that all parts of the food are exposed to the microwave field.

• Digital Display and Touch Controls: The easy-to-read LED and intuitive touch controls provide accurate timing.

• Child Safety Lock: This crucial feature prevents accidental operation by children, enhancing safety in the home. It typically works by requiring a specific sequence of button presses to unlock the microwave controls.

Addressing Common Concerns and User Feedback

• Is it safe?: Microwave ovens are incredibly safe when used according to the manufacturer’s instructions. The metal mesh you see in the door acts as a Faraday cage, preventing microwaves from escaping. The FCC (Federal Communications Commission) sets strict limits on the amount of microwave leakage allowed from ovens, and these levels are far below anything considered harmful.

• Lower Power: Some users have expressed concern about the 700-watt power. As mentioned earlier, this simply means you may need to adjust cooking times slightly. It doesn’t mean the microwave is less effective; it just means it’s more energy-efficient. Experimentation and following the guidelines in the user manual will help you find the optimal cooking times for your favorite foods.

• The Sliding Problem: One common piece of feedback is that the microwave can slide on the countertop when opening or closing the door, particularly because it’s relatively lightweight (22.5 pounds). This is a valid usability concern. While, it may be desirable to keep the oven in a fixed position. Applying non-slip mats or pads underneath the microwave is a simple and effective solution.

• Safe Practices:
  • Always use microwave-safe containers (glass, ceramic, and certain plastics labeled as microwave-safe). Never use metal containers or containers with metal trim, as they can reflect microwaves and cause sparking (arcing).
  • Be cautious when heating liquids. Superheating, where a liquid is heated above its boiling point without visible boiling, can occur. To prevent this, allow liquids to stand for a minute or two after heating, and carefully insert a spoon or stir stick before consuming.
  • Don’t operate the microwave empty. The magnetron needs something to absorb the energy; running it empty can damage the appliance.
  • Regularly clean the interior of the microwave to prevent food buildup, which can affect performance and safety.
  • Ensure the door and door seals are in good condition. Any damage could potentially lead to microwave leakage.
    

Beyond Reheating: Exploring other uses

While the EM720CB7 excels at reheating leftovers, its capabilities extend beyond that. You can use it for:

• Steaming vegetables: Place vegetables in a microwave-safe container with a small amount of water, cover, and cook on high for a few minutes.
• Cooking rice and grains: Use a microwave-safe rice cooker or follow specific instructions for cooking grains in the microwave.
• Making mug cakes: Numerous recipes are available online for quick and easy single-serving cakes made in the microwave.
• Melting butter or chocolate: Use a low power level and short intervals to avoid scorching.
• Softening butter or ice cream: Use very low power and short intervals to soften without melting.
• Poaching eggs: Use dishes designed for this use.

The Future of Microwave Cooking

Microwave technology continues to evolve. Some newer models feature:

• Inverter Technology: Provides more consistent power delivery than traditional magnetrons, resulting in more even cooking.
• Sensor Cooking: Automatically adjusts cooking time and power level based on the moisture content of the food.
• Convection Cooking: Combines microwave energy with a convection fan and heating element, allowing for baking and roasting.
• Smart Features: Some microwaves can be controlled via smartphone apps or voice assistants.

Conclusion: The Science of Convenience

The microwave oven, including the BLACK+DECKER EM720CB7, is a testament to how scientific principles can be harnessed to make our lives easier. It’s a far cry from Percy Spencer’s giant Radarange, but the fundamental science remains the same. By understanding how microwaves work and following safety guidelines, you can enjoy the speed and convenience of this everyday miracle with confidence. The EM720CB7, with its compact size, pre-programmed settings, and user-friendly design, offers a practical and affordable way to experience the benefits of microwave cooking. It’s not just about heating food; it’s about understanding the science that makes it all possible.